Image-processing device independently controlling each of functions that correct density of image

ABSTRACT

An image-processing device includes an image-reading unit that reads image data from a document optically, an image-recording unit that records the image data read onto recording paper, a first-density-correction unit that corrects first density characteristics that depend on the image-reading unit, a second-density-correction unit that corrects second characteristics to reproduce density of the document, a third-density-correction unit that corrects third density characteristics that depend on the image-recording unit, and a control unit that independently controls each of the first, second and third density-correction units to execute density correction. 
     The image-processing device can record a high-quality image by adjusting the above described density characteristics by controlling each of the first, second and third density-correction units independently.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image-processing device that readsimage data optically by use of an image-reading unit such as a scannerfrom a document, and records the image data read by the image-readingunit on recoding paper by use of an image-recording unit such as aprinter. The present invention particularly relates to animage-processing device, a method to process an image, and a recordmedium for efficiently correcting density of image data at animage-reading unit, the density of the image data at an image-recordingunit and the density of the image data controlled by a density notch.

2. Description of the Related Art

A device that includes an image-reading unit such as a copy machine, ascanner and a facsimile is commonly used recently. A device thatincludes an image-recording unit such as a printer is also commonlyused. In addition, a composite device that includes a plurality ofdevices such as a copy machine, a scanner, a facsimile and a printer hasbeen placed on the market. The above-described devices adopt variousmethods to correct density of an image. For instance, a method tocorrect density characteristics of image data that depend on theimage-reading unit by widening signal levels of the image data that isread from a document by the image-reading unit is referred to asinput-density correction. A method to correct density of image data inan electrical area by increasing and decreasing the density by anoperation using a density notch is referred to as notch-densitycorrection. A method to correct density of image data by adjustingsettings of the image-recording unit is referred to as recording-densitycorrection.

For instance, Japanese Laid-Open Patent Application No. 9-224155discloses an image-processing device that includes a plurality ofdensity-conversion methods to convert density of image data to a digitalsignal by applying several data-conversion methods, and a method toselect one of the density-conversion methods according to detection ofdensity distribution of the image data. This conventional technology isadapted to the above-described input-density correction so that theimage-processing device can easily execute density correction on varioustypes of documents such as a document wherein texture density of thedocument is high, a document wherein texts are written in low density, agraph on a graph sheet, a photograph and a drawing. However, units andmethods that execute the input-density correction and the notch-densitycorrection are combined together in the above-described image-processingdevice, and thus a user cannot control each of the input-densitycorrection and the notch-density correction separately. Additionally,the user cannot control the recording-density correction individually inthe above-described image-processing device.

Accordingly, the image-processing device can only execute theinput-density correction at its image-reading unit, but cannot executethe notch-density correction and the recording-density correctionseparately so that a high-quality output image may not be obtained bythe above-described image-processing device. For instance, when acomposite device whereto the above-described conventional technology isadapted executes a printer function, image data that has not beenprocessed through the image-reading unit is supplied from an externalapplication to the image-recording unit where the image data is recordedon recording paper, and thus the input-density correction on the imagedata at the image-reading unit is not executed. Additionally, when thecomposite device executes an image-copying function, stains are removedfrom the texture of image data read by the image-reading unit byexecuting the input-density correction at the image-reading unit.However, there is a case that an output image may not be a desirable oneby light-emitting characteristics of the image-recording unit since therecording-density correction cannot be adjusted independently by a user.

Accordingly, it is a significant issue to efficiently execute theabove-described input-density correction, notch-density correction andrecording-density correction. In other words, it is a significant issueto optimize density correction in an image-processing device such as acopy machine, a scanner, a facsimile, a printer and a composite device.

SUMMARY OF THE INVENTION

Accordingly, it is a general object of the present invention to providean image-processing device, a method to process an image, and a recordmedium for efficiently executing input-density correction, notch-densitycorrection and recording-density correction.

The above-described object of the present invention is achieved by animage-processing device including an image-reading unit that reads imagedata from a document optically, an image-recording unit that records theimage data read onto recording paper, a first-density-correction unitthat corrects first density characteristics that depend on theimage-reading unit, a second-density-correction unit that correctssecond characteristics to reproduce density of the document, athird-density-correction unit that corrects third densitycharacteristics that depend on the image-recording unit, and a controlunit that independently controls each of the first, second and thirddensity-correction units to execute density correction.

The image-processing device can record a high-quality image by adjustingthe density of the image by controlling each of the first, second andthird density-correction units independently.

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed description when readin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a structure of a composite deviceaccording to a first embodiment of the present invention;

FIGS. 2A and 2B are graphs showing characteristics of γ-correction;

FIG. 3 is a block diagram showing a switching mechanism to access a RAMfrom a CPU in the composite device;

FIG. 4 is a block diagram showing detailed structures of adensity-correction unit and a gradation-processing unit provided in thecomposite device;

FIG. 5 is a diagram showing a binary dither matrix;

FIGS. 6A, 6B and 6C are diagrams showing respectively a 4×4 dithermatrix, a 6×6 dither matrix, and a 8×8 dither matrix;

FIGS. 7A and 7B are diagrams for describing a binary-error-diffusionprocess and a multi-valued-error-diffusion process;

FIG. 8 is a block diagram showing a circuit to switch a value of athreshold between a variable threshold and a fixed threshold;

FIG. 9 is a block diagram showing a spatial-filter-processing unitprovided in the composite device;

FIG. 10 is a block diagram showing a circuit that controls switching ofdensity data of an MTF correction;

FIG. 11 is a block diagram showing a circuit that executes athreshold-setting process;

FIG. 12 is a block diagram showing an isolated-point-detection circuitto detect an isolated point;

FIG. 13 is a block diagram showing an isolated-point-correction circuitto correct the isolated point detected by the isolated-point-detectioncircuit;

FIG. 14 is a block diagram showing a video flow controlled byvideo-path-control units;

FIG. 15 is a block diagram showing a video-control system;

FIG. 16 is a block diagram showing an application-input-control unit;

FIG. 17 is a block diagram showing an application-output-control unit;

FIG. 18 is a block diagram showing an image-output-control unit;

FIGS. 19A, 19B, 19C and 19D are block diagrams showing data structuresused for transmitting data in a data bus;

FIG. 20 is a block diagram showing a smoothing function provided in thecomposite device;

FIG. 21 is a block diagram showing an image-recording-control unit;

FIG. 22 is a block diagram showing a memory module;

FIGS. 23A, 23B and 23C are graphs showing characteristics of adensity-conversion table;

FIG. 24 is a block diagram showing an image-aggregation unit to placeimages together on a single document;

FIGS. 25A, 25B and 25C are block diagrams showing an operation screenprovided in an operation unit according to a second embodiment of thepresent invention;

FIGS. 26A through 26E are graphs for describing density correctioncontrolled by the operation screen provided in the operation unit;

FIGS. 27A through 27F are block diagrams showing an operation screenprovided in an operation unit according to a third embodiment of thepresent invention;

FIGS. 28A and 28B are block diagrams showing a method to storeparameters used for setting an image-quality mode;

FIGS. 29A and 29B are block diagrams showing an operation screenprovided in an operation unit according to a fourth embodiment of thepresent invention;

FIGS. 30A and 30B are block diagrams showing the operation screen andadjustable items of an image-quality mode;

FIGS. 31A, 31B and 31C are block diagrams showing embodiments of apredetermined image-quality mode;

FIG. 32 is a block diagram showing a structure of a scanner according toa fifth embodiment of the present invention; and

FIG. 33 is a block diagram showing an image-processing system accordingto a sixth embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will now be given of preferred embodiments of the presentinvention, with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a structure of a composite deviceincluding an image-reading unit and an image-recording unit, accordingto a first embodiment of the present invention. A composite device 100shown in FIG. 1 can control input-density correction, notch-densitycorrection, and recording-density correction individually to execute themost appropriate density correction on input image data for recording ahigh-quality image. The input-density correction is a method to correctdensity of an image by use of an image signal obtained from the imagewhen the image is read by the image-reading unit. The notch-densitycorrection is a method to correct density of an image in electricitydomain by adjusting recording density of the image by a user operating adensity notch. The recording-density correction is a method to correctdensity of an image by controlling the image-recording unit.

Conventional composite devices execute the input-density correction andthe notch-density correction as a single process, whereas the compositedevice according to the first embodiment of the present invention cancontrol and execute each of the above-described correctionsindividually. Additionally, a user can adjust the recording-densitycorrection executed by the composite device according to the firstembodiment by use of a control unit provided therein. Accordingly, thecomposite device according to the first embodiment can eliminate stainson the texture of a document, can set density of an image to be adesirable value by controlling a density notch, and can adjust sharpnessof the image according to a type of the document.

The composite device 100 shown in FIG. 1 includes a document-readingunit 101, a shading-correction unit 102, an input-density-correctionunit 103, a main-scanning-multiplication unit 104, aspatial-filter-processing unit 105, a density-correction unit 106, agradation-processing unit 107, a matrix RAM (Random Access Memory) 108,a video-path-control unit 109, a recording-control block 110, animage-recording unit 111, an external application (APL) 112, anexternal-application interface (I/F) 113, a memory interface 114, amemory-control unit 115, a printer-page memory 116, a RAM 117, a ROM(Read Only Memory) 118, a CPU (Central Processing Unit) 119, anoperation unit 120, and a system bus 121.

The document-reading unit 101 is a scanner optically reading a documentprovided on a document tray not shown in FIG. 1. In other words, thedocument-reading unit 101 reads density of the document by executing anoptical image-scanning process, for instance, by emitting light from alight source onto the document, and then receiving the light reflectedon the document. The document-reading unit 101 then converts the densityof the document read by the optical image-scanning process to an analogelectric signal by use of an imaging device such as a CCD (ChargeCoupled Device), and converts the analog electric signal to a digitalelectric signal, followed by supplying the digital electric signal as adensity signal to the shading-correction unit 102. Theshading-correction unit 102 is a processing unit that correctsunevenness of the density of the document caused by the light source andthe optical image-scanning process. To be concrete, theshading-correction unit 102 reads a density signal indicating density ofa white board in advance by use of the document-reading unit 101, andstores the density signal indicating the density of the white board as astandard density signal in a memory. When receiving the density signalindicating the density of the document, the shading-correction unit 102corrects the density signal of the document for each dot at eachimage-reading line of the document in a main-scanning direction by useof the standard density signal stored in the memory. The correcteddensity signal of the document is then supplied to theinput-density-correction unit 103. The density signal of the documentafter being processed through the above-described shading correctionexecuted by the shading-correction unit 102 is linear to a reflectionrate of the light that is emitted from the light source and reflected bythe document.

The input-density-correction unit 103 is a processing unit that correctsdensity characteristics of a document depending on the document-readingunit 101, and converts a density signal supplied from theshading-correction unit 102 to another digital signal whichcharacteristic is linear to density of an image recorded on a surface ofthe document. To be concrete, the characteristics of thedocument-reading unit 101 reading an image is measured, and a conversiontable including the opposite characteristics of the document-readingunit 101 reading the image is downloaded to the RAM 117 in advance. Theinput-density-correction unit 103 converts the density signal suppliedfrom the shading-correction unit 102 to another density signal that islinear to the density of the image recorded on the document by use ofγ-correction with reference to the conversion table. Additionally, theinput-density-correction unit 103 increases density of a part of thedocument having a low density, and decreases density of a part of thedocument having a high density, thereby increasing effect of the densitycorrection.

The main-scanning-multiplication unit 104 is a processing unit thatexpands and reduces size of an image recorded on the document by eachimage-reading line by the CCD in the main-scanning direction. Themain-scanning-multiplication unit 104 expands and reduces the image byeach image-reading line with keeping an MTF of an optical systemprovided in the document-reading unit 101 by use of a convolutionmethod, so as to keep resolution of the image read from thedocument-reading unit 101. On the other hand, expansion and reduction ofthe image by each image-reading line in a sub-scanning direction aremechanically controlled.

The spatial-filter-processing unit 105 prepares for gradation processingof the image, and extracts features of the image by use of adensity-adaptation unit 105 a and an isolated-point detection/correctionunit 105 b included therein. The spatial-filter-processing unit 105further includes an MTF-correcting function, a smoothing function, anedge-segment-extracting function and a variable-threshold-settingfunction, and outputs filtered image data and a variable thresholdcalculated from various conditions for binarization to the followingdensity-correction unit 106.

The density-correction unit 106 is a processing unit that attends todensity correction of a document read by the document-reading unit 101according to image data and a variable threshold received from thespatial-filter-processing unit 105, and converts density to bereproduced according to an operation using the density notch.Additionally, the density-correction unit 106 can download anyconversion data stored in the RAM 117 for the image data and thevariable threshold, the conversion data generally being the same valuefor the image data and the variable threshold. However, thedensity-correction unit 106 can also download different conversion datafor the image data and the variable threshold to change gradationcharacteristics of an output image outputted from the image-recordingunit 111 intentionally.

The gradation-processing unit 107 diffuses density data for each pixelof the image data in a unit area, and thus converts the density data foreach pixel to data corresponding to characteristics of theimage-recording unit 111. The gradation-processing unit 107 includesvarious gradation-processing modes such as a simple-multi-valuing mode,a binarization mode, a dithering mode, an error-diffusing mode, aphase-control mode, and the like. A threshold for quantization isdiffused in a unit area for executing the diffusion of the density datafor each pixel of the image data, and the diffusion of the thresholdcarries out download of any value to the matrix RAM 108, and selectionof appropriate quantization by switching a method to access the matrixRAM 108 according to a gradation-processing mode.

The recording-control block 110 corrects edges of a line drawing bysmoothing the edges, and includes a pixel-correction unit 110 a, adensity-conversion unit 110 b and a PWM (Pulse Width Modulation) unit110 c. The pixel-correction unit 110 a and the density-conversion unit110 b execute density-conversion process considering start-upcharacteristics to electric signals in an image-forming process so as toincrease dot-reproduction characteristics preceding a PWM process. ThePWM unit 110 c modulates pulse width of laser for recording an image. Tobe concrete, the PWM unit 110 c reproduces gradation of the imagewherein collection and diffusion of dots are smoothed by making phasecontrol executed by the gradation-processing unit 107 and the phasecontrol executed by smoothing process of the pixel-correction unit 110 ainter-dependent on the PWM process.

The image-recording unit 111 reproduces the image on imprint paper bycreating, imprinting, and fusing the image on the photosensitive by useof the laser. According to the first embodiment of the presentinvention, a laser printer is used for the image-recording unit 111.However, in a case that an image-development method such by an inkjetprinter other than the laser printer is applied to the image-recordingunit 111, structures of the PWM unit 110 c and the image-recording unit111 become different from the image-recording unit 111 according to thefirst embodiment. The processes executed by the document-recording unit101 through the density-conversion unit 110 b are identical for applyingthe laser printer to the image-recording unit 111 and applying theimage-development method other than the laser printer to theimage-recording unit 111.

It should be noted that the density correction of the document executedby the input-density-correction unit 103, the density correctionexecuted by the density correction unit 106, and gradation-processingmodes set by the gradation-processing unit 107, and the densityconversion executed by the recording-control block 110 can beindividually controlled by the operation unit 120. For instance,processing modes for recording the image may be selected by use of theoperation unit 120 according to a document type, that is whether thedocument contains mainly patterns and pictures or mainly letters in thecomposite device 100. Additionally, parameters used for densitycorrection may be selected and changed by use of the operation unit 120according to density of the document. Each unit in the composite device100 is controlled by operation mode set by the operation unit 120 thatis stored in the RAM 117 through the CPU 119 and the system bus 121.

The video-path-control unit 109 controls paths for image-signal flow inthe composite device 100. To be concrete, the video-path-control unit109 controls a signal of the image scanned by the scanner provided inthe document-reading unit 101. If an A/D conversion level is 8 bitsafter reading the image data by use of the CCD, the video-path-controlunit 109 controls a path for the image-signal flow with the specific bitlength (8 bits). Additionally, the video-path-control unit 109 controlsa path through the external-application interface 113 to the externalapplication 112. Additionally, the video-path-control unit 109 controlsa data path after image-quality processing, wherein bit width of theimage signal is converted to a binary or multi-valued number so that thebit width of the image signal fits the bus width. The video-path-controlunit 109 controls input and output signals of the external application112, wherein the image signal is expressed in a binary number for theexternal application 112 requesting facsimile reception andtransmission, and printout by a personal computer. Additionally, thevideo-path-control unit 109 controls the memory interface 114 thatcompresses and expands the image data, and reading data from and writingdata in the printer-page memory 116 through the memory-control unit 115,wherein the video-path-control unit 109 transfers the image data in thebit width that matches writing characteristics of the printer-pagememory 116, which is bit width of data that the printer-page memory 116accepts.

The external-application interface 113 controls interface signalsbetween the composite device 100 and the external application 112, andcontrols paths for printing the image requested by a facsimile and acomputer, outputting the image according to a request from the scanner,and transmitting an output image from a computer by use of a facsimilefunction.

A description will now be given of the r-correction carried out by thescanner provided in the document-reading unit 101, and the densitycorrection of the document read by the scanner. FIG. 2A is a graphshowing characteristics of the γ-correction carried out by the scannerprovided in the document-reading unit 101. FIG. 2B is a graph showingthe conversion table for the density correction of the document read bythe scanner. Density characteristic 201 shown in FIG. 2A showsconversion characteristics of the image data after the shadingcorrection of the density of the image data has been executed. As seenin FIG. 2A, the density characteristic 201 is not a straight line risingsteeply at low density and being saturated with a electric signaloutputted from the scanner at high density, and thus the densitycharacteristic 201 is a general exponential function Exp(γ). The densitycharacteristic 201 is converted to a space linear to the density of thedocument by multiplying the density characteristic 201 by a curve 202that is expressed as an exponential function Exp(1/γ), and thus thedensity characteristic 201 is converted to a function linear to thedensity of the document. Accordingly, dynamic range of the densityincreases.

On the other hand, the recording-density correction multiplies a valueof characteristics after downloading the conversion table shown in FIG.2B to the RAM 117 for executing density conversion, considering affectof γ characteristics.

The conversion table shown in FIG. 2B includes several curves such as aconvex curve 203 and a concave curve 204. The convex curve 203 is usedfor reproducing a low-density part of the document. The concave curve204 is used for eliminating a low-density part of the documentcorresponding to texture of the document. Data used for recording theimage may be set to any value by selecting a combination of a processingmode for recording the image and adjustment of the density notch. Dataused for transmitting an image by uses of a facsimile can only be set toa characteristic that is linear to data or to density of the document,since the image-recording characteristics of the facsimile are unknown.However, affect of the image-recording characteristics are considerablefor copying the document, and dot-reproduction characteristic of theimage-recording system for copying the document shifts conversion thatis linear to density to the recording-control block 110 b, and setscorrection of the document by the density conversion as its mainfunction.

Density reproduction and gradation reproduction can be set to variousvalues by downloading conversion parameters to the RAM 117. The RAM 117stores data for the γ-correction of the scanner, the density correctionof the image data, the density correction according to the variablethreshold, setting of the threshold for quantization for dithering anderror-diffusion process, the smoothing process, and the densityconversion γ for the image-recording control.

A description will now be given of a method to access the RAM 117 fromthe CPU 119 and to refer to the conversion table stored in the RAM 117by the CPU 119. FIG. 3 is a block diagram showing a switching mechanismto access the RAM 117 from the CPU 119. The size of the RAM 117 can beset to any size including an address space enough for storing agradation number for each pixel of an input image. For example, if thedocument-reading unit 101 converts analog CCD data obtained from theinput image to an 8-bit digital signal, the address space in the RAM 117should be set to 8 bits at least. When the CPU 119 accesses the RAM 117for downloading reference data to the RAM 117, an address bus (CPUaddress) from the CPU 119 is selected by a multiplexer (MUX) 310 withusing a “download” signal, and an address in the RAM 117 to write thereference data in is supplied to an address terminal (ADDR) of the RAM117. Additionally, assuming that a high signal and a low signal arerespectively a data-read mode and a data-write mode, the low signal isselected by a multiplexer (MUX) 311 by using a READ/WRITE signal forwriting the reference data in the RAM 117, and then the reference datafrom the CPU 119 (CPU data) is inputted to a data input terminal (DATI)of the RAM 117.

When the CPU 119 accesses the RAM 117 for reading a value on theconversion table stored in the RAM 117, an input image data is selectedby the MUX 310 with using the download signal, and is supplied to theaddress terminal of the RAM 117. Additionally, the high signal isselected by the MUX 311 with using the READ/WRITE signal for the CPU 119to read the value on the conversion table from the RAM 117, and thus thevalue on the conversion table stored in an address that corresponds tothe input image data in the RAM 117 is calculated out from a data outputterminal (DATO) of the RAM 117. Accordingly, a structure of the RAM 117can be simplified, and time taken for arithmetic operations can beshortened since the address to write the reference data in the RAM 117and the input image data are supplied to the same input terminal, thatis, the address terminal of the RAM-117. Additionally, data stored inthe RAM 117 can be altered.

A description will now be given of the density-correction unit 106 andthe gradation-processing unit 107 with reference to FIG. 4. FIG. 4 is ablock diagram showing detailed structures of the density-correction unit106 and the gradation-processing unit 107. The density-correction unit106 includes a RAM 401 and a RAM 402. The RAM 401 stores a γ-correctiontable 411 used for density conversion of the variable threshold. The RAM402 stores a γ-correction table 412 used for density conversion of theimage data. The gradation-processing unit 107 includes a RAM 403, avariable-binarization unit 413, an edge-pixel-control unit 414, a binaryfilter 415, a dithering unit 416, an error-diffusing unit 417, amulti-value-level-conversion unit 418, and phase control units 419 and420. The RAM 403 is a matrix RAM for storing thresholds used fordithering and error diffusing of the input image data. Thegradation-processing unit 107 includes two different paths for datainputted thereto. One of the paths is used for binarization process, andthe other path is used for multi-valuing process. Simple-binarizationprocess includes processes taken by the variable-binarization unit 413,the edge-pixel-control unit 414, and the binary filter 415. Each of thedithering unit 416 and the error-diffusing unit 417 uses a single pathfor the binarization and the multi-valuing, wherein one of thebinarization and the multi-valuing is selected by data stored in the RAM403 and switching between address/switching control of the RAM 403 bythe CPU 119. The phase-control units 419 and 420 add phase informationrespectively to data processed through the error-diffusing unit 417being selected for the multi-valuing and themulti-value-level-conversion unit 418 according to density distributionof the document in the main-scanning direction of the scanner providedin the document-reading unit 101 for forming dots. For instance intriple-valuing, a signal level can be altered among values “00”, “01”,“10”, and “11” by providing 2-bit space to the signal level. Regularly,the values “00”, “01”, “10” and “11” are obtained by quad-valuing.However, density level can be expressed in the triple-valuing by settingthe value “00” to white color, the value “11” to black color, and thevalues “01 and “10” to fifty percent duty for the pulse width modulatedby the PWM so that the above four 2-bit values may be interpreted asthree values. The value “01” turns on the laser onto a right half of anarea for forming dots with right phase. On the other hand, the value“10” turns on the laser onto a left-half of the area for forming dotswith left phase. The phase and the density are defined by the phasecontrol units 419 and 420 being linked with the PWM unit 110C.

A description will now be given of a method to download a binary dithermatrix to the RAM 403 provided in the gradation-processing unit 107 whenthe RAM 403 includes the 8-bit address space with reference to FIG. 5.FIG. 5 is a diagram showing a binary dither matrix 501. Each box shownin FIG. 5 indicates a pixel. Size of the binary dither matrix 501 may beselected by any combination of 4, 6, 8, or 16 pixels in themain-scanning direction and 4, 6, 8, or 16 pixels in the sub-scanningdirection. The combination of the pixels and pattern data are actuallyselected according to a necessary line number and line decimation of animage. Additionally, each pixel in the binary dither matrix 501 storedin the RAM 403 is not accessed sequentially but in two dimensions basedon a two-dimensional arrangement of pixels in the binary dither matrix501, and thus control of the RAM 403 is simplified.

A description will now be given of a method to access the RAM 403 as amulti-valued dither matrix with reference to FIGS. 6A, 6B and 6C. FIGS.6A, 6B and 6C are diagrams showing respectively a 4×4 dither matrix, a6×6 dither matrix, and 8×8 dither matrix. Each pixel in the dithermatrixes shown in FIGS. 6A, 6B and 6C is triple-valued. The number ofaddresses in the main-scanning direction necessary for each pixel in thedither matrixes shown in FIGS. 6A, 6B, and 6C is twice as much as thenumber of addresses in the sub-scanning direction necessary for eachpixel. For instance, two addresses are provided for each pixel in themain-scanning direction for a 4×4 dither matrix 601 shown in FIG. 6A,and eight addresses are referred when accessing the matrix 601.Additionally, a pixel A includes thresholds A0 and A1, and density ofthe pixel A is compared with the thresholds A0 and A1. Similarly, eachpixel in the matrix 601 is provided with two thresholds, and density ofeach pixel is compared with the thresholds provided therein.

The thresholds A0 and A1 are set to values so that the threshold A0 issmaller than the threshold A1 for the left pulse. Additionally, thethreshold A0 is set to a value greater than a value of the threshold A1for the right pulse. If the density of the pixel A is smaller than thethresholds A0 and A1 when comparing the density of the pixel A with thethresholds A0 and A1 provided therein, a pulse code “00” is set to aperiod for keeping the laser on for every segment of a pulsing area as aresult of quantization of the density of the pixel A. If the density ofthe pixel A is greater than the thresholds A0 and A1, a pulse code “11”is set to the period for keeping the laser on. Else, the density of thepixel A is between the thresholds A0 and A1, and a pulse code “01” isset to the period for keeping the laser on when a right pulse system(right phase) is provided for forming the dots, and a pulse code “10” isset to the period when a left pulse system (left phase) is provided forforming the dots. Similarly, a pulse code is generated for each pixel ina 6×6 dither matrix 602 shown in FIG. 6B and a 8×8 dither matrix 603shown in FIG. 6C by downloading threshold arrangements to the RAM 403considering phase generation.

A description will now be given of binary and multi-valuederror-diffusing processes with reference to FIGS. 7A and 7B. Theerror-diffusing unit 417 provided in the gradation-processing unit 107is shown in FIG. 7A, and includes an adder 701, a N-valuing unit 702, aRAM 703, an error-calculating unit 704, an error memory 705, anerror-weighting unit 706, a comparator 707, and acorrection-data-generating unit 708. Initially, the comparator 707compares an input pixel with a density threshold inputted thereto, anddirects the correction-data-generating unit 708 to generate a correctiondata. The correction data generated by the correction data generatingunit 708 is then added to or subtracted from the input pixel by theadder 701 to decrease roughness of low density part of the input image,thereby adding a processing mode that adds any data to the input pixel.Subtraction of the correction data is executed by the adder 701 byproviding a complement that indicates the subtraction as a part of thecorrection data. The N-valuing unit 702 executes N-valuing of dataoutputted from the adder 701 based on a threshold for quantizationcorresponding to result of calculation between the input image anderrors supplied from the RAM 703 after selecting a variable thresholdfor the threshold for quantization between a fixed threshold and thevariable threshold. The N-valued data outputted from the N-valuing unit702 is then supplied to the error-calculating unit 704. Theerror-calculating unit 704 calculates an error between the dataoutputted from the adder 701 and the N-valued data supplied from theN-valuing unit 702, and supplies the calculated error to the errormemory 705. The error memory 705 holds the error received from theerror-calculating unit 704 for a certain period, and supplies to theerror-weighting unit 706. The error-weighting unit 706 then weights theerror, and supplies the weighted error to the adder 701 where theweighted error is added to the input pixel. As described above, regulartexture of the input image is generated by adding the correction data toeach pixel in the input image. Additionally, dots (pixels) areconcentrated in a unit area of the input image by adding the error(noise) to each pixel therein, and thus effective dots are amplified.

When a variable threshold is used as the threshold for quantization, athreshold that repeats by a unit block is stored in the RAM 403 of thegradation-processing unit 107. FIG. 7B shows a binary 8×8 variable areaincluding a threshold 710. The texture of the image data is reduced bychanging the threshold 710 in a block. Additionally, storage of edges ofthe image data and reproduction of the gradation are adjusted byproviding fixed thresholds and variable thresholds in the 8×8 matrix.When executing the multi-valued error-diffusing process, each of thepixels in the matrix includes a plurality of thresholds, andquantization (pulse) code is set for the pixel by use of the thresholds.The phase is rearranged according to the density distribution in themain-scanning direction. The error memory 705 includes a one-line FIFOmemory. The error-weighting unit 706 includes a coefficient of twolines, each line including five pixels, for instance. It should be notedthat the size of the matrix and the coefficient distribution may bealtered.

A description will now be given of switching a threshold forquantization between a variable threshold and a fixed threshold withreference to FIG. 8. The threshold for quantization is switched byselecting a processing mode through the system bus 121. A variablethreshold 801 stored in the RAM 403 is altered by address control in themain and sub scanning direction, and by multi-valued level when theerror-diffusing mode is selected as a processing mode. If the simplebinarization process is selected, the variable threshold 801 is set to athreshold that is set and which density is corrected by thespatial-filtering unit 105. A fixed threshold 802 is not a value fixedby hardware, but is a value set by the CPU 119 in a register. Inaddition, the value of the fixed threshold 802 may be changed accordingto a processing mode and characteristics of the image data. One of thevariable threshold 801 and the fixed threshold 802 is selected by amultiplexer (MUX) 803, and is supplied to a comparator 804 where theselected threshold is compared with the input image data.

A description will now be given of a structure of the spatial-filteringunit 105 with reference to FIG. 9. A two-dimensional image matrix 901 isprovided in the spatial-filtering unit 105 by use of a plurality of linememories 902. Frequency characteristics of the image data in thetwo-dimensional image matrix 901 are corrected, and features areextracted from the density characteristics. An MTF-correction unit 903can select any MTF-correction coefficients and correction rate for eachof the main and sub scanning directions individually to correct the MTFof the optical system, and can support various types of processingmodes, documents, and optical systems. An isolated-point-detection unit904 detects a noise in the texture of the document and in the image ofthe document by detecting regularity in the arrangement of the pixels onthe image data, and then deciding whether a pixel that does not obey theregularity is an isolated point or a part of a meshed image. Anisolated-point-elimination unit 905 selects and executes eitherelimination of the isolated point detected by theisolated-point-detection unit 904 completely, or replacement of theisolated point detected by the isolated-point-detection unit 904 withaverage of pixels surrounding the isolated point. Additionally, theisolated-point-elimination unit 905 eliminates noises on the image. Aline thinning/thickening unit 906 thins and thickens line density ineach of the main and sub directions individually and adjusts balance ofline-density reproductions in the main and sub scanning directionsaccording to an MTF-correction coefficient. A smoothing unit 907eliminates moiré generated by a meshed image and an aliasing noise atA/D conversion, and extracts information for setting a variablethreshold. An edge-detection unit 908 detects edge segments inhorizontal, vertical, left-slanted, and right-slanted direction, andgenerates a switching signal for optimizing filtering process and acontrol signal for selecting a variable threshold. A selector 909selects an MTF corrected video path for an edge-forming element offiltered image data. A variable-threshold-setting unit 910 sets athreshold for each pixel to be binary according to output signals fromthe smoothing unit 907 and from edge-detection unit 908.

A description will now be given of switching control related to densitydata of an MTF correction with reference to FIG. 10. An MTF correctionis executed on a focused pixel. A correction coefficient and a scalefactor are switched among range of the density level. Initially, anupper limit 1001 and a lower limit 1002 of a threshold are set forselecting a density level. The switching control is executedindividually in each of a density range higher than the upper limit 1001(UPPER), a density range between the upper limit 1001 and the lowerlimit 1002 (MIDDLE), and a density lower than the lower limit 1002(LOWER). Additionally, a correction coefficient 1003 and a scale factor1004 are individually set in each of the UPPER density range, the MIDDLEdensity range, and the LOWER density range. Accordingly, animage-filtering process is optimized for each density range so thatgradation of each pixel is stably reproduced. In addition to thecorrection coefficient 1003 and the scale factor 1004, a fine-adjustmentcoefficient 1005 is set and added to the focused pixel after the MTFcorrection for executing weak MTF correction on the focused pixel.

A description will now be given of a threshold-setting process withreference to FIG. 11. A density-level-deciding unit 1101 compares theupper limit 1001 and the lower limit 1002 stored in a register for thesmoothed image signal. The smoothed image signal is supplied to aselector 1102 if a value of the smoothed image signal is between theupper limit 1001 and the lower limit 1002. The upper limit 1001 issupplied to the selector 1102 if the value of the smoothed image signalis above the upper limit 1001. The lower limit 1002 is supplied to theselector 1102 if the value of the smoothed image signal is below thelower limit 1002. Then, the selector 1102 selects either an outputsignal from the density-level-deciding unit 1101 or a fixed thresholdstored in a register by use of an edge signal to output the selectedsignal as a variable threshold therefrom. In a case that the variablethreshold outputted from the selector 1102 is a threshold thatcompletely depends on the density of the texture of the image, the fixedthreshold is selected by the selector 1102 as the variable threshold fora non-edged part. The output signal from the density-level-deciding unit1101 is selected by the selector 1102 as the variable threshold for anedged part.

A description will now be given of a method to detect an isolated pointwith reference to FIG. 12. An isolated-point-detection circuit shown inFIG. 12 includes a 5×5 matrix 1201, a 7×7 matrix 1202, a 9×9 matrix1203, an isolated-point-decision unit 1204, a state-change-decision unit1205, and a data-comparison unit 1208. If a focused pixel, that is, apixel located in the center of a matrix is completely isolated frompixels located at inside edges of the matrix, the pixel is called anisolated point (isolated pixel). The 7×7 matrix 1202 is used forrecoding an image which size is equal to that of an original image, andthe isolated point sized 4×4 can be detected at maximum. When recordingthe image which size is reduced than that of the original image, spacebetween the isolated point and its surrounding pixels is reduced.Accordingly, a 2×2 pixel should be detected in the 5×5 matrix 1201 so asto detect a 4×4 isolated point which size is reduced by 50%. On theother hand, when recording the image which size is expanded to more than200% of the size of the original image, the 4×4 isolated point is alsoexpanded, and thus the 9×9 matrix 1203 must be used to detect theisolated point that remains on the image. It should be noted that avalue “kmx” is supplied by the CPU 119 to a selector so as to select anappropriate matrix among the matrixes 1201, 1202 and 1203. Additionally,a value “kath” and image data are supplied to a matrix.

A dither pattern with low density is removed in addition to an isolatedpoint from the image by detecting the isolated point only by use of therelation between the isolated point and its surrounding pixels, anddeleting the detected isolated point in a matrix such as the 5×5 matrix1201 and the 9×9 matrix 1203, the dither pattern being usefulinformation on the image. Consequently, detection and deletion of theisolated point are limited by adding a process to compare the image datasupplied by the CPU 119 with a threshold “kbth” supplied by the CPU 119and a state-changing process to the detection of the isolated point.

In FIG. 12, a value T1 indicates whether the focused pixel is anisolated point, a white pixel, or others. If the focused pixel isdetected as an isolated point or a white pixel, the value T1 becomes“1”. Otherwise, the value T1 becomes “0”. Subsequently, the value T1 issupplied to the isolated-point-decision unit 1204 and thestate-change-decision unit 1205. The data-comparison unit 1208 decideswhether the focused pixel is a white pixel by comparing the image dataand the threshold “kbth”; and then supplies a value T2 to theisolated-point-decision unit 1204 and the state-change-decision unit1205. If the value of the focused pixel is smaller than the threshold“kbth”, the focused pixel is detected as a white pixel, and the value T2becomes “1”. If the value of the focused pixel is larger than thethreshold “kbth”, the focused pixel is detected as a non-white pixel,and thus the value T2 becomes “0”. The state-change-decision unit 1205counts the number of white pixels that are continuously placed in amatrix (1206), and measures size of an isolated point (1207) from thevalues T1 and T2. The state-change-decision 1205 then decides whichstate the focused pixel is in among states PAPER, DOT, and PICTURE. Thestate PAPER where detection of the type of the focused pixel startsindicates that the focused pixel is a part of an area where white pixelsare continuously placed. The state DOT indicates that the focused pixelis actually an isolated point. Additionally, the state PICTURE indicatesthat the focused pixel is a part of a pattern, a letter, a mesh, or anarea where the white pixels are not placed continuously and widely.Information about a state wherein the focused pixel is in addition tothe values T1 and T2 is supplied to the isolated-point-decision unit1204, where the focused pixel is determined as either an isolated pointor not, and the result is outputted therefrom as a “result” signal.

A description will now be given of a method to correct an isolated pointdetected by the isolated-point-detection circuit with reference to FIG.13. An isolated-point-correction circuit shown in FIG. 13 includes acorrection-strength-calculation unit 1301 and a selector 1302. A signal“mtfo” is image data after being processed through the MTF correction.The image data “mtfo” and an isolated point have been emphasized by theMTF correction so that quality of a copied image becomes worse byrepeating a process to copy the image. Accordingly, the isolated pointis smoothed with its surrounding pixels or is replaced by a white pixelinstead od being processed through the MTF correction. A signal “kmod”is supplied to the selector 1302, and selects to execute anisolated-point-correction process or not. If theisolated-point-correction process is to be executed, a signal “ktj”switches a correction level in the correction-strength-calculation unit1301. The correction-strength-calculation unit 1301 set conversion ofthe isolated point to a white level as a maximum correction strength,and then weakens the correction level to 1/32, ⅛, and ½ of the imagedata “mtfo”.

A description will now be given of a video flow controlled byvideo-path-control units with reference to FIG. 14. FIG. 14 includesvideo-path-control units 1401 and 1402, an image-processing unit 1403, avideo-control-unit interface (VCU I/F) 1404, an image-memory unit (IMU)1405, an application-output unit (APL-output unit) 1406, anapplication-input unit (APL-input unit) 1407, an application-inputinterface (APL-input I/F), a multiplication filter, and an IMU interface(IMU I/F). The multiplication filter shown in FIG. 14 is a last unitthat processes image data before passing the image data to theimage-processing unit 1403. The image data is filtered by beingprocessed through the shading correction, the γ-correction, themultiplication of the image data, and the MTF correction. The image datathat has been through the above-described correction processes isreferred to as an image-signal, and the image signal is supplied to theimage-processing unit 1403 through the video-path-control unit 1401. Theimage-processing unit 1403 executes the density correction and thegradation processing of the image signal received through thevideo-path-control unit 1401. The density correction sets a density bymatching the image signal to recording characteristics of theimage-recording system by use of an area-gradation method that considersrecording of the image data onto paper. The image-processing unitadditionally executes multi valuing and binarization of the imagesignal. The video-path-control unit 1402 receives the image signal fromthe image-processing unit 1403 after the image signal is being processedby the image-processing unit 1403, and mainly controls paths of theimage signal being binary. The VCU I/F 1404 converts a format of theimage signal received from the video-path-control unit 1402 to a dataformat of the image-recording system.

In addition to a regular video path from the image-reading system to theimage-recording system, the video-path-control units 1401 and 1402control video paths to the image memory unit (IMU) 1405 through the IMUI/F, and to an external application unit. The IMU 1405 includes buffermemories for a scanner and a printer, and the like. The externalapplication unit includes a facsimile, a printer, a scanner, and thelike. For instance, the video-path-control unit 1401 supplies the imagesignal that is multi-valued through a path SA for a scanner applicationto the application-output unit 1406. The image-processing unit 1403supplies the image signal as a facsimile-transmission signal that isbinary through a path FAX to the application-output unit 1406.Additionally, the video-path-control unit 1402 receives a binary imagesignal as a printer-application signal from the application-input unit1407 through path PA and the application-input interface (APL-inputI/F).

A description will now be given of a video-control system with referenceto FIG. 15. A signal “S” shown in FIG. 15 indicates an image signalafter being processed through the shading correction, the multiplicationof the image signal, and the filtering processes as described above.Units “A”, “MS”, “MP”, “P”, “F”, and “M/B” are respectively, aninterface (I/F) terminal connecting to an external application, a buffermemory for a scanner, each module in a buffer memory for a printer, animage-recording system located next to the PWM unit 110 c, a facsimileunit, and a motherboard connecting external application units. Acharacter “G” indicates a combination of the image signal and an imagesignal stored in a memory. Selectors SEL1 through SEL6 are provided inthe video-control system for switching a video path. The video-controlsystem shown in FIG. 15 includes only a signal path for multi valuingand binarization. In other words, an image-processing unit provided inthe video-control system includes a single RAM for storing a dithermatrix and a single FIFO memory for the error-diffusion process forexecuting multi valuing and binarization for the reason of simplifying acircuit structure of the video-control system. Consequently, a binaryerror diffusion process and multi-valued-error-diffusion process cannotbe executed concurrently. However, the binary-error-diffusion processand the multi-valued-error-diffusion process may be executed almostconcurrently by use of a time-partition process. All the images to beprocessed through a plurality of operations are scanned initially by thescanner, and are stored in the buffer memory MS. Subsequently, theimage-processing unit executes only the binarization and multi-valuingprocesses on the image signals stored in the buffer memory MS, andreproduces the most appropriate image signals.

There are two different methods to process jobs when the video-controlsystem has received a job that includes an execution of themulti-valued-error-diffusion process and a job that includes anexecution of the binary-error-diffusion process almost simultaneously,for example, a job that executes the multi-valued-error-diffusionprocess on first image data, and then generates five copies of the firstimage data, and a job that executes the binary-error-diffusion processeson second image data, and then executes facsimile transmission of thesecond image data. One of the methods stores the image data for both ofthe jobs described above in the buffer memory MS. The other methodstores the first image data for executing themulti-valued-error-diffusion process in the buffer memory MS, andreleases the image-processing unit for the binary-error-diffusionprocess when the video-control system receives a request to execute thebinary-error-diffusion process on the second image data.

The first method executes the binary-error-diffusion process on thesecond image data after executing the multi-valued-error-diffusionprocess on the first image data, and stores the second image data in anarea of the buffer memory MS different from the area of the buffermemory MS wherein the first image data is stored while executing themulti-valued-error-diffusion process on the first image data. To beconcrete, initially, the first image data for generating five copies isread by the scanner, and is supplied through a path S, S1, SEL3, and MSto the buffer memory MS, followed by being stored in the buffer memoryMS. The first image data stored in the buffer memory is then suppliedthrough a path MS, S9, S10, SEL5, the image-processing unit, S3, SEL2,S13, and P to the image-recording system P, thereby converting thedensity of the first image data, and executing themulti-valued-error-diffusion process on the first image data by use ofthe image-processing unit, followed by printing the first image data byuse of the image recoding system P. The video-control system prints outfive copies of the first image data by repeating the above-describedprocess for five times. While printing out the first image data by useof the image-recording system P, the scanner (an image-reading system)is not being used, and can accept a job to transmit the second imagedata by use of a facsimile. Accordingly, the second image data isscanned by the scanner, and is supplied through the path, S, S1, SEL3,and MS to the buffer memory MS, followed by being stored in the buffermemory MS. The path to read image data from the buffer memory MS and thepath to store the image data in the buffer memory MS are not overlappedto each other, so that both of the first of second image data are safelystored in the buffer memory MS. After the five copies of the first imagedata are printed by the image-recording system P, the second image datastored in the buffer memory is supplied through a path MS, S9, S10,SEL5, the image-processing unit, S3, SEL1, S12, A, M/B, and F to thefacsimile unit F, thereby converting the density of the second imagedata, and executing the binary-error-diffusion process on the secondimage data by use of the image-processing unit, followed by transmittingthe second image data by use of the facsimile unit F.

The second method interrupts the copying process of the first image dataif the second image data for the facsimile transmission is scanned bythe scanner while reading the first image data from the buffer memory MSand printing the first image data by use of the image-recording systemP. Even if the interruption of the copying process of the first imagedata is occurred, the first image data has been already stored in thebuffer memory MS so that it is not necessary to reread the first imagedata again by use of the scanner. The second image data is supplied tothe facsimile unit F by taking a path S, S1, SEL5, the image-processingunit, S3, SEL1, S12, A, M/B, and F to the facsimile unit F, where thesecond image data is transmitted therefrom. Subsequently, the firstimage data is read from the buffer memory MS, and is copied by theimage-recording system so that the five copies of the first image dataare printed as described above.

Additionally, a description will be given of paths that a combinedprocess of external applications takes in the video-control system withreference to FIG. 15. For instance, a combined process of outputtingfirst image data scanned by the scanner to a scanner application SA, andsupplying second image data received from a personal computer as aprinter application PA to the facsimile unit F without processing thesecond image data through the image-processing unit provided in thevideo-control system. The first image data is scanned by the scanner,and is supplied through a path S, S1, SEL1, S12, A, M/B, and SA to thescanner application SA. While the first image data is being scanned bythe scanner, the second image data received from the personal computercan be transmitted from the facsimile unit F by switching a physicalswitch on the motherboard M/B, and then by taking a path PA, M/B, and Fto the facsimile unit F. If the scanner application SA is being used byother units or devices, the first image data is stored in the buffermemory MS temporarily. When the scanner application SA is released fromthe use by the other units, the first image data stored in the buffermemory MS is transmitted to the scanner application SA by taking a pathMS, S9, S10, S4, SEL1, S12, A, M/B, and SA. While transmitting the firstimage data to the scanner application SA, the scanner (image-readingsystem) and the image-recording system P are available for copying imagedata. For instance, when printing out the image data by binary copyingprocess, the image data scanned by the scanner is supplied to the buffermemory MP through a path S, S3, SEL3, and MP. The image data stored inthe buffer memory MP is then supplied through a path. MP, S9, S10, S4,SEL2, S13, and P to the image-recording system P, where the image datais printed out therefrom. Additionally, while outputting the image datafrom the buffer memory MP, the scanner is available for reading anotherimage data, and the image data scanned by the scanner can be stored ineither of the buffer memories MS and MP.

A description will now be given of an application-input-control unitwith reference to FIG. 16. The application-input-control unit shown inFIG. 16 includes an input-mask unit 1601, a FIFO-writing-control unit1602, a FIFO (First-In First-Out) memory 1603 and a FIFO-reading-controlunit 1604. The application-input-control unit is an interface unit thatobtains image data synchronous to a clock that is asynchronous to asystem clock provided in the composite device 100. The input-mask unit1601 masks an area on an image data to white except an effective imagearea that has been received from an external application, and reversesan image level of the image data since the composite device 100 definesa white pixel and a black pixel respectively as a low level and a highlevel, whereas an interface regulation between the composite device 100and an external application regularly sets the white pixel and the blackpixel respectively as the high level and the low-level. Subsequently,the input-mask-un it 1601 supplies the image data to the FIFO memory1603 after executing a masking process by the control of theFIFO-writing-control unit 1602.

The composite device 100 receives 7015-bit image data recorded at 600dpi on a sheet of paper which width and length are respectively A4-sizedand 297 mm at maximum from the external application. Additionally,binary image data is carried through the composite device 100 in 8-bitparallel data format, and thus data storage format of the FIFO memory1603 is 1K×8 bit to store the 7015-bit image data therein. TheFIFO-writing-control unit 1602 generates a write-reset signal “xwrst”and a write-enable signal “xweb” from a line-synchronous signal“XARLSYNC” from the external application based on a clock signal“XARCLK” supplied also from the external application as a standard clocksignal. An assertion: time of the signal “XARLSYNC” corresponds to acycle of the clock signal “XARCLK”. Additionally, theFIFIO-writing-control unit controls writing of the image data to theFIFO memory 1603 by use of the signals “xwrst” and “xweb”. TheFIFO-reading-control unit 1604 generates control signals, and specifiesa data format for the image data read from the FIFO memory 1603. To beconcrete, the FIFO-reading-control unit 1604 generates a read-resetsignal “xrrst” and a read-enable signal “xreb” based on theline-synchronous signal “XARLSYNC”, the both signals being synchronousto the system clock of the composite device 100. Additionally, theFIFO-reading-control unit 1603 receives, binary image data, that is,8-bit parallel data, from external applications such as facsimile and aprinter, and converts the 8-bit parallel data to 1-bit serial data byuse of a shift register to output to an image memory unit (IMU). Inother words, the shift register converts the 8-bit parallel data to the1-bit serial data by one bit, and sets unused bits to “0”. TheFIFO-reading-control unit 1603 also outputs the 8-bit parallel data toan image-recording system (VCU) without converting a data format of the8-bit parallel data.

A description will now be given of an application-output-control unitwith reference to FIG. 17. The application-output-control unit shown inFIG. 17 includes an output-gate-conversion unit 1701, animage-level-reversing unit 1702, a data-format-conversion unit 1703, anMSB/LSB reversing unit 1704, and an output-timing-adjustment unit 1705.The application-output-control unit is an interface unit that outputsimage data processed in the composite device 100. Theoutput-gate-conversion unit 1701 executes a gate (aneffective-image-area-regulation signal) conversion only in themain-scanning direction. To be concrete, the output-gate-conversion unit1701 coverts the length of a gate in the main-scanning direction to aspecified length, wherein the length can be set to a value between 0 dotand 8191 dot. The output-gate-conversion unit 1701 is mainly used forcutting out an image by use of a scanner application, wherein a shiftingfunction of a multiplication unit is used for cutting the image in themain-scanning direction. This output-gate-conversion unit 1701 can beturned on and off depending on an operation executed on the image data.A conversion of a scanner-reading gate is executed at the maximumdocument size, and an edge of the image data to be outputted aftermultiplication of the image data is calculated. Subsequently, the edgeof the image data is matched with an edge of an effective image area inthe main-scanning direction (LGATE) by an image shifting process, andthen the gate length is matched with the length in the main-scanningdirection. The image is cut out in the sub-scanning direction by settinga gate length in the sub-scanning direction by use of a timing-controlunit. Matching to a data format is specified by the length of the LGATEafter the gate conversion by a dot. The length of the LGATE is convertedaccording to the selected data format. If the image data is 8-bitmulti-valued data or 1-bit binary serial data, the length of the LGATEremains as it has been set. If the image data is 8-bit binary paralleldata, the length of the LGATE is converted to ⅛ of the length that hasbeen set. If there exists a remainder from the division of the length,the length of the LGATE is set to a rounded-up value.

The image-level-reversing unit 1702 receives image data as a signalaokd[7:0] from units in the composite device 100, and reverses an imagelevel of the image data since the composite device 100 defines a whitepixel and a black pixel respectively as a low level and a high level,followed by passing the image data to the data-format-conversion unit1703. The data-format-conversion unit 1703 selects a data format for theimage data to be outputted to an external application among fourdata-formatting methods. The first data-formatting method does notconvert the data format of the image data, and outputs the image data asmulti-valued data read by a scanner or as serial binary image data. Thesecond data-formatting method outputs 6 bits from the most significantbit in the 8-bit image data as 6-bit data after masking the least 2 bitsin the image data excluding the 6-bit data to white, wherein the 6-bitdata can be shifted to the most-significant-bit (MSB) side, or to theleast-significant-bit (LSB) side. The third data-formatting processoutputs 4 bits from the most significant bit in the 8-bit image data as4-bit data after masking the least 4 bits in the image data excludingthe 4-bit data to white, wherein the 4-bit data can be shifted to theMSB side or to the LSB side. Additionally, the fourth data-processingmethod outputs binary 8-bit parallel data after executing 8-bit packingon binary image data when transmitting the binary image data only by useof the MSB in an 8-bit bus. In this case, the MSB is processed throughthe 8-bit packing initially. The MSB/LSB reversing unit 1704 switcheseach bit from the MSB to the LSB in the 8-bit bus, or from the LSB tothe MSB, and can execute the MSB/LSB reversing process for 1-bit binary,4-bit multi-valued, 6-bit multi-valued, 8-bit multi-valued, and 8-bitbinary packing. Subsequently, the MSB/LSB reversing unit 1704 suppliesthe image data to the output-timing-adjustment unit 1705.

The output-timing-adjustment unit 1705 outputs the image data and gatesignals to an external application synchronously to a rising edge of anoutput clock “XAWCLK”. Each clock is generated by a clock-generatingmodule provided in the composite device 100, and is supplied to aninterface unit (I/F). When transmitting 8-bit multi-valued data and1-bit binary data to an external application, a clock which cycle andfrequency are identical to those of the system clock is supplied to theinterface unit. When transmitting 8-bit binary parallel data to theexternal application, a clock which cycle is ⅛ of the cycle of thesystem clock is supplied to the interface unit.

A description will now be given of an image-output-control unit withreference to FIG. 18. The image-output-control unit shown in FIG. 18controls outputting image data that has been processed through thecomposite device 100, and includes an output-timing-adjustment unit 1801for gate signals, a FF unit 1802, and a selector 1803. Theoutput-timing-adjustment unit 1801 outputs image data that has beenprocessed through printer masking and gate signals that regulates aneffective image area of the image data to the selector 1803. Moreprecisely, the output-timing-adjustment unit 1801 outputs the image dataand the gate signals that are to be supplied to the image-recordingsystem (VCU), after setting output timing of the image data and the gatesignals synchronous to a rising edge of a clock signal “XPCLK” used foroutputting data to a VCUL. The clock signal “XPCLK” is generated by theclock-generating module provided in the composite device 100 such thatthe clock signal “XPCLK” has the same phase as the system clock.Additionally, the clock-generating unit generates the clock signal“XPCLK” which clock cycle is half the system clock cycle when the imagedata is 4-bit multi-valued data. When the image data is 2-bitmulti-valued data, the cycle of the clock signal “XPCLK” is ¼ of thesystem clock cycle. When the image data is 8-bit binary data, the cycleof the clock signal “XPCLK” is ⅛ of the system clock cycle. The imagedata and the gate signals are set synchronous to the clock signal“XPCLK”, and include a maximum phase difference of eight system clockcycles from a line-synchronous signal “XPLSYNC” that is supplied fromthe image-output-control unit to the VCU. The image data and the gatesignals are processed at a rising edge of a system clock “clk”, andtiming to output the image data and the gate signals to the selector1803 is adjusted by a reversed system clock “xclk” in theoutput-timing-adjustment unit 1801. The selector 1803 selects the imagedata and the gate signals supplied from the output-timing-adjustmentunit 1801 or data supplied from the application-input-control unit byuse of an application-input-selection signal, and outputs the selecteddata set synchronous to the clock signal “XPCLK” therefrom to aninterface.

A description will now be given of a data structure with reference toFIGS. 19A through 19D. A data bus used for supplying data to theimage-recording system (VCU) is 8-bit wide, and includes signal lines“xpde[2:0]”, “se”, “xpdo[2:0]”, and “so” for transmitting densityinformation and phase information. A bit assignment of the signal linesare based on the bit assignment of the signal lines for transmitting4-bit multi-valued data, and is changed according to a data format ofthe data transmitted through the data bus. There are four types of dataformats that are, 4-bit multi-valued, 2-bit multi-valued, binary, and8-bit multi-valued formats for the data transmitted through the databus. Even-numbered pixels and odd-numbered pixels are transmitted inparallel in the 4-bit multi-valued format. Four pixels are transmittedin parallel in the 2-bit multi-valued format. Eight pixels aretransmitted in parallel in the binary format. Additionally, a dataformat of data is converted for transmitting the data serially throughthe data bus in the 8-bit multi-valued format.

FIG. 19A shows a bit assignment of the signal lines for transmitting4-bit multi-valued data through the data bus. The signal line xpde[2:0]is used for transmitting density information of even-numbered pixels.The signal line “se” is used for transmitting phase information oradditional density information of the even-numbered pixels. The signalline xpdo[2:0] is used for transmitting density information ofodd-numbered pixels. The signal line “so” is used for transmitting phaseinformation or additional density information of the odd-numberedpixels. FIG. 19B shows a bit assignment of the signal lines fortransmitting 2-bit multi-valued data through the data bus. If the phaseinformation is included in the data transmitted through the data bus, abit assignment takes a form used for transmitting information abouttriple-valued density. If the phase is fixed, a bit assignment takes aform for transmitting information about quad-valued density. The first,second, third and fourth pixels are provided respectively to the signallines xpde[2:1], [xpde[0], se], xpdo[2:1], and [xpdo[0], so].

Additionally, FIG. 19C shows a bit assignment of the signal lines fortransmitting binary data through the data bus. The bit assignment shownin FIG. 19C converts an image data to 8-bit parallel data for the 8-bitdata bus by assigning information about eight pixels to the signal linesxpde[2], xpde[1], xpde[0], “se”, xpdo[2], xpdo[1], xpdo[0], and “so” inorder. FIG. 19D shows a bit assignment of the signal lines firtransmitting 8-bit multi-valued data through the data bus. In the bitassignment shown in FIG. 19D, 8-bit density information of each pixel isprovided to the signal line [xpde[2:0], se, xpdo[2:0], so], wherein eachbit of the information is provided to a bit-wide slot in the signal linesuch that the most significant bit (MSB) of the 8-bit densityinformation is provided to the slot xpde[2], and the least significantbit is provided to the slot “so”.

A description will now be given of a smoothing function provided in thecomposite device 100 with reference to FIG. 20. An image-smoothing unitshown in FIG. 20 includes an image matrix 2001, a jaggy-correction unit2002, an isolated-point-correction unit 2003, anerror-diffusion-enhancing unit 2004, a dithering unit 2005, apixel-averaging unit 2006, an edging unit 2007, and a selector 2008. A9-lines×13-pixels two-dimensional matrix is created in the image-matrix2001 by generating delay data that includes 13 pixels for each of 9lines in the main-scanning direction based on data supplied through the9 lines. Each of the units following the image-matrix 2001 accesses theimage-matrix 2001 simultaneously, and executes binary/multi valuedconversion process except the edging unit 2007. The edging unit 2007does not need any data from the image matrix 2001, and processes datasupplied from a single line. The jaggy-correction unit 2002 including acode generator and a RAM, generates 12-bit code data by executing apattern-matching process by use of arranged data in the image matrix2001, and inputs the generated data to an address provided in the RAM.The RAM provided in the jaggy-correction unit 2002 is used for imagecorrection, and outputs image-correction data corresponding to the datainputted thereto. The image-correction data should be downloaded to theRAM before the pattern-matching process.

The isolated-point-correction unit 2003 detects an isolated point in the9×13 matrix including a focused point by the pattern-matching process. Apixel detected as an isolated point is removed by a masking process, orpixels are added to an two-dimensional area surrounding the pixeldetected as the isolated point to create a set of pixels that do notconsist an isolated point. The masking process and the addition ofpixels to the isolated point can be selected by switching an operationmode of the composite device 100 to be executed or not. An isolated dotcauses unevenness of density in an image-recording area since there arecases that the isolated dot is reproduced or not reproduced according toimage-recording processes and image-recording conditions of animage-recording system, and thus causes deterioration of image quality.Accordingly, dot density of the isolated dot should be increased so thatthe isolated dot can be reproduced stably, or can be eliminated from theimage. The error-diffusion-enhancing unit 2004 smoothes texture of theimage by use of a band-path filter that keeps line drawings on theimage, and generates a phase signal based on an order of pixels in themain-scanning direction.

The dithering unit 2005 converts data in the image matrix 2001 to amulti-valued signal virtually by executing a 5×5 or 9×9 low-passfiltering process on a binary dithering pattern provided from the imagematrix 2001. The pixel-averaging unit 2006 takes an average of pixelsadjacent to each other, and generates phase information for themulti-valued signal. The dithering unit 2005 executes each of 5×5, 7×7,and 9×9 filtering processes for smoothing the 9×13 matrix by use of asmoothing filter provided therein. The smoothing filter provided in thedithering unit 2006 receives a 1-bit binary signal from the image matrix2001, and eliminates a high-level signal element from the 1-bit binarysigal. Subsequently, the pixel-averaging unit 2006 takes an averagebetween an even-numbered pixel and an odd-numbered pixel in themain-scanning direction for a pixel to be smoothed. A value of thesmoothed pixel is the average of the even-numbered pixel and theodd-numbered pixel. The pixel-averaging unit 2006 then generates2-dotted image data after setting the even-numbered pixel as a rightphase and the odd-numbered phase as a left phase. The selector 2008selects a density signal and a phase signal among density signals andphase signals supplied from each unit connected to the selector 2008,and then converts the selected density signal and phase signalrespectively to a 4-bit signal and a 2-bit signal to output therefrom.

A description will now be given of an image-recording-control unit withreference to FIG. 21. The image-recording-control unit shown in FIG. 21includes a clock-speed-conversion FIFO memory 2101, a smoothing module2102, a multi-valued-signal-processing unit 2103, a density-conversionunit 2104, and a selector 2105. Image data inputted to theimage-recording system from the video-path-control unit 109 is one ofimage data scanned by a scanner provided in the document-reading unit101, image data stored in a memory module, and image data received fromthe external application 112. Since each clock provided in the scanner,the memory module and the external application 112 for processing pixelsis not synchronous to a clock used for recording image data according topixel density of the image data, the image-recording-control unitincludes a 2-port RAM mechanism in its clock-speed-conversion FIFOmemory 2101 to convert a clock speed used for processing the image data.Image data is initially recorded in a RAM provided in theclock-speed-conversion FIFO memory 2101 at a first clock speed, and thenis read from the RAM at a second clock speed, thereby converting theclock speed for processing the image data.

Subsequently, the image data read from the RAM provided in theclock-speed-conversion FIFO memory 2101 is supplied to the smoothingmodule 2102 and the multi-valued-signal-processing unit 2103, where in adata format of the image data is converted. The smoothing module 2102converts binary image data to multi-valued data. Themulti-valued-signal-processing unit 2103 executes a conversion processof a phase signal. The density-conversion unit 2104 includes a pluralityof density-conversion tables, and converts density level of the imagedata by use of the tables in parallel, considering density-reproductioncharacteristics of an image-forming process, after receiving themulti-valued data from the smoothing unit 2102 and themulti-valued-signal-processing unit 2103. Data stored in each table inthe density-conversion unit 2104 is downloaded by the CPU 119.Additionally, the data downloaded by the CPU 119 and used for convertingdensity of the image data is controlled in detail for the mostappropriate reproduction of the image, considering changes in theprocessing mode, usage of a printer, reception of an image by afacsimile, copy of an image scanned by a scanner, a document that mainlyincludes texts, copy of a printed document, and copy of a photo.Subsequently, the selector 2105 selects image data which density levelhas been converted by the density-conversion unit 2104 according to aprocessing mode. The image data selected by the selector 2104 isgenerated as a latent image on an image-forming unit by turning a laserdiode (LD) on and off by controlling a phase and a power of the laserdiode (LD) by use of a PM (Pulse Modulation) and a PWM (Pulse-WidthModulation).

A description will now be given of a memory module with reference toFIG. 22. The memory module shown in FIG. 22 includes a memory interface(I/F) 2201, a work area 2202, a memory bank 2203, address-control units2204 and 2210, a data-compression unit 2205, a memory-writing-controlunit 2206, a memory-reading-control unit 2207, and a data-expansion unit2208. The memory interface 2201 controls input and output of image data.The work area 2202 includes a RAM for storing data to process the imagedata. The memory bank 2203 is a memory area used for storing the imagedata, and includes a non-electric memory such as a RAM, a HDD, a MO, aCD-RW, a DVD, and the like. The work area 2202 is used for executingbit-map expansion on input image data and output image data. The inputimage data and the output image data can be expanded individually to amemory area with any memory address by the address-control unit 2204.For instance, mixture of input image data and a bit map expanded fromimage data stored in the memory bank 2203, aggregation of two images,rotation of an image, addition of a printing pattern such as a date ontoinput image data are executed in the work area 2202. Image data isstored in the memory bank 2203 by the memory-writing-control unit 2206after being compressed by the data-compression unit 2205 for effectivelyallocating memory areas in the memory bank 2203. This data compressionregularly encodes image data in reverse conversion. However, non-reverseconversion of the image data can be executed as long as image quality ofa reproduced image does not decrease visually. When storing the inputimage data in the memory bank 2203 by use of the memory-writing-controlunit 2206, ID information and property information of the input imagedata such as an input system where the input image is supplied from anda processing mode, are attached to the input image data.

The memory-reading-control unit 2207 reads image data from the memorybank 2203. The image data read by the memory-reading-control unit 2207is expanded by the data-expansion unit 2208 to a bit map. The propertyinformation of image data affects bit-map expansion of the image dataoccasionally. However, the property information of the image data isbasically used for controlling the above-described imagerecording-control unit to set appropriate parameters for recording animage, and is especially used for controlling a selection ofdensity-conversion tables provided in the image-recording-control unit.

A description will now be given of an embodiment of a density-conversiontable with reference to FIGS. 23A, 23B and 23C. Characteristics of adensity-conversion table can be linear to data inputted thereto in acase that a binary density level is to be reproduced. Linear data isdownloaded by the CPU 119 to the density-conversion table so that anoutput density level becomes equal to an input density level.Characteristics 2301 of the color-conversion table shown in FIG. 23A canbe adapted to conversion of density level of image data in a case thatthe density of the image data is set to the most appropriate densitylevel by being processed through γ-correction executed by a scannerprovided in the document-reading unit 101 or density correction, and ina case that a γ-process executed in an image-forming unit is linear toan input signal. In a case that tone reproduction of the image data isimportant, data linear to density should be downloaded in order tocorrect linearity of the process. FIGS. 23B and 23C respectively showcharacteristics 2302 and 2303 of the density-conversion table. Thecharacteristics 2302 and 2303 of the density-conversion table arebetween characteristics linear to density and characteristics linear todata, and are used for reproducing a balance between texts and patternsin a case that the image data includes the texts and the patterns.Additionally, data downloaded to the density-conversion table areaffected by a dot formation. It is generally hard to reproduce a one-dotisolated point, but is fine to reproduce density in an area wherein dotsand lines are clustered together. The data downloaded to thedensity-conversion table is further affected by a modulation method forcontrolling the laser diode (LD), and image processing for tonereproduction. Accordingly, various data and elements are necessary forgenerating the density-conversion table.

A description will now be given of an image-aggregation unit 2401 toplace images together on a single document with reference to FIG. 24.FIG. 24 shows a case that images A, B, C and D are read by a scanner,and their image sizes are reduced so that all the images can be fit on asingle printing paper. It is assumed that the images A and D includemainly texts, the image B includes patterns, and the image C includestexts and patterns. The images A and D, the image B, the image C areread by the scanner respectively in a text mode, a photo mode, and atext/photo mode, and are stored in the memory module. Characteristics ofthe γ-correction executed by the scanner, a filter used for the MTFcorrection, the density γ-correction are set differently for each of theimages A and D, the image B, and the image C. Additionally,characteristics of “γ” of the density conversion are differently set foreach of the images A and D, the image B, and the image C by respectivelysetting resolution of the images A and D, gradation of the image B, andthe balance of the texts and the patterns in the image C to the firstpriority.

When the images are stored in the memory module, parameters that excludecharacteristics of the memory-writing control and are used in animage-processing system are read to the memory module, andcharacteristics necessary to write the images in the memory module areadded to properties of the images stored therein. For instance, in thetext mode, density-conversion characteristics necessary for the textmode or assumed density-conversion characteristics are added to theproperties. The images are aggregated in the work area 2202 of thememory module, and the aggregated image is outputted to theimage-recording-control unit through the video-path-control unit 109.When aggregating the images by use of the work area 2202, addresseswhere the images are connected to each other in the main-scanning andsub-scanning directions are extracted from the property information ofthe aggregated image, and counter control is executed. The aggregatedimage is supplied to the density-conversion unit 2104 of theimage-recording-control unit, and density conversion of the aggregatedimage is executed by switching the density-conversion table to be usedamong at least three types of the density-conversion tables according tocharacteristics of the aggregated image. The contents of thedensity-conversion table can be replaced depending on an emphasizedelement such as the texts and the patterns in the aggregated image.

According to the first embodiment of the present invention as describedabove, the input-density correction executed by theinput-density-correction unit 103, the density correction executed bythe density-correction unit 106, and the recording-density correctionexecuted by the recording-control block 110 can be individuallycontrolled by processing modes selected by a user. Accordingly, thedensity correction of image data can be executed by the composite device100 in the most appropriate combination of processing modes.

Since the first embodiment of the present invention makes a user tocontrol the input-density correction, the notch-density correction andthe recording-density correction individually, the selection of theprocessing modes by the user is diverse. Consequently, the user mighthave to repeat test printing often for setting the most appropriatecombination of the processing modes. To solve the above-describedcomplication of setting the most appropriate processing mode, acomposite device that stores combinations of settings for theinput-density correction, the notch-density correction and therecording-density correction in the operation unit 120 of the compositedevice is provided according to a second embodiment of the presentinvention so that the composite device can record an image in aprocessing mode or a recording mode that is the most appropriate for atype of an input document and for characteristics of recording theimage. It should be noted that the composite device according to thesecond embodiment includes identical units and functions as thecomposite device according to the first embodiment except its operationunit 120, and thus a description of the units in the composite deviceaccording to the second embodiment corresponding to the units in thecomposite device according to the first embodiment is omitted.

A description will now be given of an operation screen with reference toFIGS. 25A, 25B and 25C. An operation screen 2500 shown in FIG. 25A isprovided in the operation unit 120 of the composite device 100, andincludes a texture-elimination key 2501, an image-aggregation key 2502,an initialization key 2503, a first-image-quality key 2504, asecond-image-quality key 2505, and a density notch 2506. Thetexture-elimination key 2501 is operated for selecting atexture-tracking level that is a parameter used for reading density oftexture of an input document by use of an image-reading system includingthe document-reading unit 101 among fixed settings. For instance, thetexture-elimination key 2501 controls the image-reading system toeliminate the texture of the input document completely, or to keep lowdensity signals of the texture. Additionally, the texture-eliminationkey 2501 controls a threshold level used for eliminating density signalsafter selecting the texture-tracking level. A conversion table for thescanner γ correction is switched according to the selectedtexture-tracking level also by the texture-elimination key 2501.

The image-aggregation key 2502 is used for turning an image-aggregationprocess in the memory module on and off. For instance, the number ofinput documents to be aggregated onto a single printing paper isselected by the image-aggregation key 2502. A method to aggregate theinput documents is set by the initialization key 2503. Thefirst-image-quality key 2504 and the second-image-quality key 2505 areused for selecting an image-processing mode for recording an image. Forinstance, the image-processing mode can be a text mode, a photo mode, atext/photo mode, and a special-document mode, each of the modes notbeing fixed. The image-processing mode is set by the initialization key2503, and only frequently used image-processing modes are displayed onthe operation screen 2500. Infrequently used image-processing modes areselected by use of the initialization key 2503. When the density of adocument to be recorded has been changed by the density notch, a setvalue of an image-reading table is switched to a value corresponding tothe changed density.

The initialization key 2503 is also used for selecting image-processingmodes, and for providing the selected image-processing modes to each ofthe first-image-quality key 2504 and the second-image-quality key 2505.To be concrete, image-processing modes with setting 1 through setting Nare prepared as shown in FIG. 25B, and the two most frequently usedimage-processing modes are set to the first-image-quality key 2504 andthe second-image-quality key 2505, for example, the image-processingmode with the setting 1 to the first-image-quality key 2504, and theimage-processing mode with the setting 3 to the second-image-quality key2505. If all of the image-processing modes with the setting 1 throughthe setting N are displayed on the operation screen 2505, a selection ofthe image-processing modes are increased, thereby satisfying a pluralityof needs for recording an image. However, operability of the operationunit 120 decreases if the number of the image-recording modes that areactually used is small. The settings 1 through N can cover the mostimage-reading and image-reading conditions. However, any additionalmodes can be created for operating the composite device 100 in a specialmode.

Parameters for a setting can be collected in a group to be registered asan image-processing mode by use of the initialization key 2503. As shownin FIG. 25C, an image-processing mode that is customized to match aspecific environment for operating the composite device 100 can beexecuted by grouping various parameters for each setting to create agroup of the parameters, and combining desirable parameter set values2507 with the group of the parameters to create a new setting, followedby assigning the new setting to the first-image-quality key-2504.

A description will now be given of density correction controlled by theoperation screen 2500 provided in the operation unit 120 with referenceto FIGS. 26A through 26E. As shown in FIG. 26A, each of an input-densitycorrection 2602, a notch-density correction 2603 and a recording-densitycorrection 2604 can be executed individually by controlling each of thecorrection using the operation screen provided in the operation unit2601. The operation unit 2601 corresponds to the previously describedoperation unit 120. Additionally, the notch-density correction 2603 isdensity correction executed according to adjustment of the density notchas described above. The input-density correction 2602 is executed byselecting one of curves M1 through M4 from a graph shown in FIG. 26B.The notch-density correction 2603 is executed by selecting one of linesN1 through N4 from a graph shown in FIG. 26C if an input documentcontains mainly texts, and one of lines P1 through P4 from a graph shownin FIG. 26D if an input document contains mainly photographs and images.The recording-density correction 2604 is executed by selecting one oflines Q1 through Q4 from a graph shown in FIG. 26E.

However, it is not simple to select the most appropriate combination ofthe parameters used for each of the above-described correction.Accordingly, it is suggested to set the parameters M1, N2, and Q3 to thefirst-image-quality key 2504 by use of the initialization key 2500 asdescribed with reference to FIG. 25 so that the input-density correction2602, the notch-density correction 2603, and the recording-densitycorrection 2604 corresponding respectively to each of the parameters M1,N2 and Q3 can be executed just by selecting the first-image-quality key2504. According to the second embodiment of the present invention asdescribed above, a desirable output image is obtained by executing asimple operation, and more precisely by registering a combination ofsettings and parameters that are used for the input-density correctionexecuted by the input-density-correction unit 103, the densitycorrection executed by the density-correction unit 106, and therecording-density correction executed by the recording-control block110.

A description will now be given of an operation screen according to athird embodiment of the present invention with reference to FIG. 27. Inthe third embodiment of the present invention, groups of parametersdefined as characteristics of density, characteristics of a filter areinitially supplied to user of the composite device as predeterminedimage-quality modes, since it is not simple for a general user to selectthe most appropriate combination of the parameters for setting imagequality for recording an image. Accordingly, the user can select animage-quality mode that satisfies the user's needs, and additionally canset another image-quality mode by use of a predetermined image-qualitymode as a customizing sample, thereby increasing the operability of thecomposite device by the user. It is preferred to keep a currentimage-quality mode being used by the user after adjustment of thecomposite device has been executed in a maintenance mode by aprofessional service man in order to increase the operability of thecomposite device by the user. The thirds embodiment of the presentinvention relates to a method to adjust an absolute value for eachsetting of the composite device in a case that a service man adjustssettings of the composite device in a maintenance mode when a change inthe setting is necessary.

An operation screen 2700 shown in FIG. 27A includes a display unit 2701,a texture-elimination key 2702, an image-aggregation key 2703, aninitialization key 2704, a first-image-quality key 2705, asecond-image-quality key 2706, a density notch 2707, a ten key 2708, aclear/stop (C/S) key 2709, and a start key 2710. On the other hand, anoperation screen 2720 shown in FIG. 27B includes an image-quality-key2725 and a light-emitting diode (LED) 2726 instead of thefirst-image-quality key 2705 and the second-image-quality key 2706. Theoperation screen 2720 shown in FIG. 27B distinguishes a selectedimage-quality key that is one of the first-image-quality key 2705 andthe second-image-quality key 2706 by use of the LED 2726. For instance,the turned-on LED 2726 may indicate that the first-image-quality key2705 is selected. On the other hand, the turned-off LED 2726 mayindicate that the second-image-quality key 2706 is selected.

The texture-elimination key 2702 is operated for selecting atexture-tracking level that is a parameter used for reading density oftexture of an input document by use of an image-reading system includingthe document-reading unit 101 among fixed settings. For instance, thetexture-elimination key 2702 controls the image-reading system toeliminate the texture of the input document completely, or to keep lowdensity signals of the texture. Additionally, the texture-eliminationkey 2702 controls a threshold level used for eliminating density signalsafter selecting the texture-tracking level. A conversion table for thescanner γ correction is switched according to the selectedtexture-tracking level.

The image-aggregation key 2703 is used for turning an image-aggregationprocess in the memory module on and off. For instance, the number ofinput documents to be aggregated onto a single printing paper isselected by the image-aggregation key 2703. A method to aggregate theinput documents is set by the initialization key 2704. Thefirst-image-quality key 2705 and the second-image-quality key 2706 areused for selecting an image-processing mode for recording an image. Forinstance, the image-processing mode can be a text mode, a photo mode, atext/photo mode, and a special-document mode, each of the modes notbeing fixed. The image-processing mode is set by the initialization ey2704, and only frequently used image-processing modes are displayed onthe operation screen 2700 and operation screen 2720. Infrequently usedimage-processing modes are selected by use of the initialization key2704. When the density of a document to be recorded has been changed bythe density notch, a set value of an image-reading table is switched toa value corresponding to the changed density.

A description will now be given of a method to set an image-qualitymode. Image-quality modes provided to the first-image-quality key 2705and the second-image-quality key 2706 are selected by use of theinitialization key 2704. FIG. 27C shows a method to select animage-quality mode among predetermined image-quality modes, and toregister a new image-quality mode. FIG. 27F shows a method to select animage-quality mode among predetermined image-quality modes, and toadjust the selected image-quality mode if small adjustment of theselected image-quality mode is necessary. Animage-quality-mode-selection screen 2740 includes image-quality modes“text document 1” 2741, “text document 2” 2742 and “text document 3”2743 that are suitable for reading and recording a text document.Additionally, the image-quality-mode-selection screen 2740 includesimage-quality modes “photo image 1”2744, “photo image 2” 2745 and “photoimage 3” 2746 that are suitable for reading and recording a photodocument that mainly includes photographs and images. Additionally, theimage-quality-mode-selection screen 2740 includes image-quality modes“special document 1” 2747, “special document 2” 2748 and “specialdocument 3” 2749 that are suitable for reading and recording a specialdocument. The two most frequently used image-quality modes are assignedto the first-image-quality key 2705 and the second-image-quality key2706. A plurality of image-quality modes that can be applied to variousimage qualities may be displayed on the operation screen 2700 to satisfyvarious types of needs from users. However, the number of theimage-quality modes that are actually used is not large so that theoperability of the composite device decreases by displaying theplurality of image-quality modes on the operation screen 2700.Accordingly, an image-quality mode is selected to be displayed on theoperation screen 2700 depending on the frequency of the image-qualitymode being used.

The image-quality-mode-selection screen 2740 further includes aregistered-image-quality mode 2739.

The image-quality modes provided in the image-quality-mode-selectionscreen 2740 can be adapted to the most environments for operating thecomposite device. However, a special image-quality mode can be createdby grouping various parameters for each setting to create a group of theparameters, and combining desirable parameter set values with the groupof the parameters to create a new setting, followed by assigning the newsetting to the registered-image-quality mode 2739. The composite device100 can execute image processing in a special environment by assigningthe registered-image-quality mode 2739 to the first-image-quality key2705.

FIGS. 27D and 27E are respectively parameter-setting screens 2750 and2760. When a process to set the registered-image-quality mode 2739 isexecuted by use of the initialization key 2704, the parameter-settingscreen 2750 appears in the display unit 2701. The parameter-settingscreen 2750 shows controllable modules by setting their parameters.Items shown in the parameter-setting screen 2750 are an input-densitycorrection 2751, a notch-density correction 2752, a recording-densitycorrection 2753, a filtering process 2754, an isolated-point elimination2755, gradation processing 2756, and pixel correction 2757. When one ofthe items is selected, another screen including adjustable items forcontrolling image quality is displayed. For example, theparameter-setting screen 2760 is displayed when the filtering process2754 is selected. The parameter-setting screen 2760 is a screen forsetting MTF correction, and includes adjustable parameters such as amain-scanning coefficient 2761 and main-scanning correction strength2762. Additionally, a current set value 2763 and a setting range 2764are displayed for each of the adjustable parameters so that a user canset values for the adjustable parameters in detail. The set values forthe adjustable parameters can be inputted as absolute values or inrelative values. The main-scanning correction strength 2762 is set byinputting a relative value, for example. Range from the strongest to theweakest for the main-scanning correction strength is divided into aplurality of relative set values to be selected by a user. Afterselecting one of the relative set values for the main-scanningcorrection strength, the selected relative set value is converted to anabsolute value by the CPU 119.

FIG. 27F shows operation screens 2780 and 2790 for a user to adjustparameters of a currently provided image-quality mode in detail. Theuser can decide to select an image-quality mode among the predeterminedimage-quality modes or to customize one of predetermined image-qualitymodes by selecting one of a “select image-quality mode” item 2791 and a“customize image-quality mode” item 2792 provided in the operationscreen 2790. The “select image-quality mode” item 2791 is selected forselecting an image-quality mode among predetermined image-quality modes2781 through 2789, and then assigning the selected image-quality mode toone of the first-image-quality key 2705 and the second-image-qualitymode 2706. The “customize image-quality mode” item 2792 is selected foradjusting a predetermined image-quality mode that has been assigned tothe first-image-quality key 2705. The current set value 2763 and thesetting range 2764 for the predetermined image-quality mode that hasbeen assigned to the first-image-quality key 2705 is displayed in theparameter-setting” screen 2760 by selecting the “customize image-qualitymode” item 2792 for the first-image-quality key 2705, and thus thepredetermined image-quality mode can be customized by changing thecurrent set value 2763. It is possible to register a new image-qualitymode in addition to the predetermined image-quality mode in theabove-described case. However, the newly registered image-quality modecannot be selected as the other predetermined image-quality modes. Amethod to register a new image-quality mode is used as a method toadjust a predetermined image-quality mode that has been assigned to oneof the first-image-quality key 2705 and the second-image-quality key2706.

A description will now be given of a method to store parameters used forsetting an image-quality mode with reference to FIGS. 28A and 28B. Fixedset values and variable set values are separated from each other and aremanaged by storing fixed set values in a ROM area and storing variableset values in a non-volatile memory area. FIG. 28A shows a memorystructure mainly used for assigning the registered-image-quality mode2739 to one of a first-image-quality mode 2830 and asecond-image-quality mode 2831. FIG. 28B shows a memory structure usedfor adjusting a predetermined image-quality mode that has been assignedto one of the first-image-quality mode 2830 and the second-mage-qualitymode 2831.

As shown in FIG. 28A, parameters for predetermined image-quality modes“text document 1” through “special document 3” are stored in a ROM 2800,and are supplied to a system. For instance, set values for theimage-quality mode “text document 1” are stored in an address “A” 2801of the ROM 2800, and set values for the image-quality mode “specialdocument 3” are stored in an address “N” 2802 of the ROM 2800. On theother hand, parameters of the registered-image-quality mode 2739 arestored in an address “bb” 2821 of a non-volatile memory 2820 so that theparameters, which are objects of customization, can be adjusted.Parameters of the first-image-quality mode 2830 and parameters of thesecond-image-quality mode 2831 are not stored in the non-volatile memory2820. Instead, addresses of image-quality modes that have been assignedto the first-image-quality mode 2830 and the second-image-quality mode2831 are respectively stored in an address “aa” 2822 and an address “ab”2823 of the non-volatile memory 2820, thereby decreasing the size of thememory being used. It should be noted that each of the addresses of theimage-quality modes that have been assigned to the first-quality mode2830 and the second-image-quality mode 2831 is located in one of the ROM2800 and the non-volatile memory 2820. When the first-image-quality key2705 is selected in the operation screen 2700, the address of theimage-quality mode that has been assigned to the first-image qualitymode 2830 is read from the address “aa” 2822 of the non-volatile memory2820, and then parameters of the image-quality mode stored in one of theROM 2800 and the non-volatile memory 2820 are downloaded to a RAM thatis used as a work area of the system. Subsequently, the system executesnecessary processes on the downloaded parameters.

In the memory structure shown in FIG. 28B, when one of the predeterminedimage-quality modes “text document 1” through “special document 3” isassigned to either the first-image-quality mode 2830 or thesecond-image-quality mode 2831, all the parameters of an assignedpredetermined image-quality mode stored in the ROM 2800 are copied to anaddress in the non-volatile memory 2820, or the address of thepredetermined image-quality mode is stored in the non-volatile memory2820. When customizing the predetermined image-quality mode assigned toone of the first-image-quality mode 2830 and the second image qualitymode 2831, each of the parameters of the predetermined image-qualitymode is overwritten with a new value for adjusting the parameters, andthen is stored in the same address as before in the non-volatile memory2820 if all the parameters of the predetermined image-quality mode arecopied to the non-volatile memory 2820. On the other hand, if theaddress of the predetermined image-quality mode that has been assignedto one of the first-image-quality mode 2830 and the second-image-qualitymode 2831 is stored in either the address “aa” 2822 or the address “ab”2823 of the non-volatile memory 2820, only new values for adjusting theparameters are stored as additional information in one of the address“aa” 2822 and the address “ab” 2823 of the non-volatile memory 2820 withthe address of the predetermined image-quality mode in the ROM 2800.When initializing the first-image-quality mode 2830 and thesecond-image-quality mode 2831, new values for adjusting the parametersof the predetermined image-quality mode are deleted from thenon-volatile memory 2820.

A description will now be given of an operation screen provided in anoperation screed provided in an operation unit according to a fourthembodiment of the present invention with reference to FIGS. 29A and 29B.The fourth embodiment increases the operability of the operation unitand the composite device 100 in addition to the above-described previousembodiments. It is preferred that a current image-processing mode or acurrent image-quality mode being used by a user is kept after adjustingparameters and settings of the composite device by a professionalservice man. The fourth embodiment especially relates to a method toadjust current set values by increasing and decreasing the set valuesfor each of parameters provided in an image-quality mode in a case thata change in settings of the composite device is necessary. An operationscreen 2900 shown in FIG. 29A includes a display unit 2901, atexture-elimination key 2902, an image-aggregation key 2903, aninitialization key 2904, a text-mode key 2905, a photo-mode key 2906,density notch 2907, a ten key 2908, a clear/stop (C/S) key 2909, and astart key 2910.

The texture-elimination key 2902 is operated for selecting atexture-tracking level that is a parameter used for reading density oftexture of an input document by use of an image-reading system includingthe document-reading unit 101 among fixed settings. For instance, thetexture-elimination key 2902 controls the image-reading system tocompletely eliminate the texture of the input document, or to keep lowdensity signals of the texture. Additionally, the texture-eliminationkey 2902 controls a threshold-level used for eliminating density signalsafter selecting the texture-tracking level. A conversion table for thescanner γ correction is switched according to the selectedtexture-tracking level also by the texture-elimination key 2902.

The image-aggregation key 2903 is used for turning an image-aggregationprocess in the memory module on and off. For instance, the number ofinput documents to be aggregated onto a single printing paper isselected by the image-aggregation key 2903. A method to aggregate theinput documents is set by the initialization key 2704.

The text-mode key 2905 and the photo-mode key 2906 are used forselecting an image-processing mode appropriate for recording an image.For instance, the image-processing mode can be a text mode, a photomode, a text/photo mode, and a special-document mode, each of the modesnot being fixed. The image-processing mode is set by the initializationkey 2904, and only frequently used image-processing modes are displayedon the operation screen 2900. Infrequently used image-processing modesare selected by use of the initialization key 2904, thereby increasingthe operability of the operation unit. When the density of a document tobe recorded has been changed by the density notch, a set value of animage reading table is switched to a value corresponding to the changeddensity.

Image-quality modes to be assigned to the text key and the photo key areselected by the initialization key 2904. A method to adjust imagequality for customizing an image-quality mode and a method to select theimage-quality mode are shown in FIG. 29B. A text mode 2921 and a photomode 2922 are initially set to a “text document 1” image-quality modeand a “photo document 1” image-quality mode respectively as factorysettings as shown in an operation screen 2920. The “text document 1”mode and the “photo document 1” mode are selected for the text mode 2921and the photo mode 2922 by a manufacturer of the composite deviceassuming that most general users of the composite device use theabove-mentioned two modes frequently. A user can operate the compositedevice generally in the “text document 1” mode and the “photo document1” mode. However, there is a case that the user prefers to adjust someof parameters provided to the text mode 2921 and the photo mode 2922. Insuch case, one of image-quality modes predetermined by the manufacturerof the composite device considering needs of a market can be selected.However, if a selection of the image-quality modes predetermined by themanufacturer does not satisfy the needs of the user, customization of apredetermined image-quality mode that satisfies the needs of the userthe most among the predetermined image-quality modes is necessary.

A predetermined image-quality mode can be selected among a “textdocument 1” mode 2931, a “text document 2” mode 2932, and a “textdocument 3” mode 2933 as an image-quality mode appropriate to record atext document. An image-quality mode appropriate for recording a photodocument can be selected among a “photo document 1” mode 2934, a “photodocument 2” mode 2935, and a “photo document 3” mode 2936. Additionally,an image-quality mode appropriate for recording a special document canbe selected among a “special document 1” mode 2937, a “special document2” mode 2938, and a “special document 3” mode 2939. Each of thetext-mode key 2905 and the photo-mode key 2906 is assigned with afrequently used predetermined image-quality mode. It should be notedthat text-mode key 2905 and the photo-mode key 2906 are not necessarilyassigned with a text document mode and a photo document moderespectively. A plurality of image-quality modes that can be adapted tovarious image qualities may be displayed on the operation screen 2900 tosatisfy various types of needs from users. However, the number of theimage-quality modes that are actually used is not large so that theoperability of the composite device decreases by displaying theplurality of image-quality modes on the operation screen 2900.Accordingly, an image-quality mode is selected to be displayed on theoperation screen 2700 depending on the frequency of the image-qualitymode being used.

A description will now be given of adjustable items related toimage-quality adjustment and a method to adjust image quality. Animage-quality mode should be initially selected among the predeterminedimage-quality modes shown in an initialization screen 2930 for adjustingparameters of the image-quality mode. For example, when customization ofthe “text document 2” mode 2932 is executed to satisfy needs of a user,the “text document 2” mode 2932 is initially selected by choosing a“mode selection” item 2951 included in an operation screen 2950. Animage-quality mode may be selected in the operation screen 2900.Alternatively, an image-quality mode may be selected by specifying anumber provided to the image-quality mode after providing consecutivenumbers to the predetermined image-quality modes in the initializationscreen 2930.

Adjustable items 2952 displayed on the operation screen 2950 includes,for example, a reading-density correction 2953, and are adjusted byinputting relative values to set values of the adjustable items 2952.For instance, in a case that the “text document 2” mode 2932 has beenselected for changing the adjustable items 2952 thereof, set values 2970of the adjustable items 2952 are displayed as a value “0”. The setvalues 2970 that are set to “0” are not absolute values but standardizedvalues according to parameters of the “text document 2” mode 2932supplied from the initialization screen 2930. A user or an operator addsa value “1” to the standardized set value “0”corresponding to thereading-density correction 2953 to increase strength of thereading-density correction 2953 relatively to standard strength of thereading-density correction 2953 of the “text document 2” mode 2932.Similarly, the user or the operator subtracts a value “1” from thestandardized value “0” to decrease the strength of the reading-densitycorrection 2953 relatively the standard strength of the reading-densitycorrection 2953. A value “1” is added to the standardized set value “0”of a “sharpness: low-density area” item 2959 to increase sharpness oflow-density area of a document than the sharpness set by a manufacturer.A value “2” is added to the standardized set value “0” of the“sharpness: low-density area” item 2959 to increase sharpness of thelow-density area of the document than the sharpness set by adding “1” tothe standardized value “0”. Alternatively, a value “1” is subtractedfrom the standardized set value “0” of the “sharpness: low-density area”item 2959 to decrease sharpness of the low-density area of the documentthan the sharpness set by the manufacturer.

Each of set values given to the adjustable items 2952 of thepredetermined image-quality modes selected by the “mode selection” item2951 is initially set to a value “0”. For instance, when the “textdocument 1” mode 2931 is selected by the “mode selection” item 2951 ofthe operation screen 2950, a set value given to a “recording-densitycorrection: solid area” item 2954 is standardized o a value “0”. Astandard strength for the “recording-density correction: solid area”item of the “text document 1” mode 2931 and that of the “text document2” mode 2932 are different. However, it is unnecessary to notify a userabout the difference in the standard strength of the recording-densitycorrection of the “text document 1” mode 2931 and the “text document 2”mode 2932. Each of the parameters for a predetermined image-quality modeis preferably set to a standard set value. “0” when the predeterminedimage-quality mode is selected by use of the “mode selection” item 2951displayed in the operation screen 2950. The adjustable items 2952 of animage-quality mode are displayed in the display unit 2901 of theoperation screen 2900 according to the image-quality mode that has beenselected. Since some of the adjustable items 2952 are not effective inthe most of the predetermined image-quality modes, the display unit 2901generally does not show all of the adjustable items 2952.

A description will now be given of image-quality adjustment in theoperation screen 2950 with reference to FIGS. 30A and 30B. FIG. 30Ashows the operation screen 2950 when customizing the “text document 1”mode 2931. FIG. 30B shows the operation screen 2950 when customizing the“photo document 2” mode 2935. The adjustable items 2952 in the operationscreen 2950 shown in FIG. 30A does not include an item “sharpness: linedrawing (soft)” 2956, whereas the adjustable items 2952 in the operationscreen 2950 shown in FIG. 29B includes the item “sharpness: line drawing(soft)” 2956, since a request for adjusting the sharpness of texts in atext document is mainly to sharpen the lines of the texts so that anitem to-soften the liens of the texts is unnecessary for a text documentmode. Accordingly, the item “sharpness: line drawing (soft)” 2956 is notdisplayed in the operation screen 2950 when the “text document 1” mode2931 is selected. For adjusting a density level of the item“reading-density correction” 2953 to be higher or darker, the set value2970 for the item 2953 should be set from a value “0” to a value “1”.

When the “photo document 2” mode 2935 is selected to be customized, theadjustable items 2952 of the “photo document 2” mode 2935 does notinclude items such as an item “sharpness: line drawing (sharp)” 2955that is not related to smooth an image on a photo document as shown inFIG. 30B since the “photo document 2” mode 2935 is an image-quality modethat is used for recording an image with smoothed gradation. Each of theadjustable items 2952 of the “photo document 2” mode 2935 is adjusted bysubstituting a numerical value for a standardized value “0” relatively.

FIGS. 31A, 31B and 31C show embodiments of a predetermined image-qualitymode. A text mode 3100 for reading and recording a text document, aphoto mode 3120 for a photo document that mainly includes photographsand images and a special mode 3130 for a special document arerespectively shown in FIGS. 31A, 31B and 31C. Each of the modes isprovided with three types of image-quality modes. However, the number ofthe modes provided to each of the text mode 3100, the photo mode 3120and the special mode 3130 may be increased or decreased if necessary.For example, the text mode 3100 includes a “text document 1” mode 3101,a “text document 2” mode 3102 and a “text document 3” mode 3103. The“text document 1” mode 3101 reproduces a text document faithfully. The“text document 2” mode 3102 reproduces texts on the text documentclearly. The “text document 3” mode 3103 reproduces texts written by useof a pencil clearly. Additionally, the photo mode 3120 includes a “photodocument 1” mode 3121, a “photo document 2” mode 3122 and a “photodocument 3” mode 3123. The “photo document 1” mode 3121 reproducesgradation levels of a printed matter such as a photogravure. The “photodocument 2” mode 3122 reproduces gradation levels of a silver-saltphotograph. The “photo document 3” mode 3123 determines detailed use ofcolors on a printed matter such as a map. Additionally, the special mode3130 includes a “special document 1” mode 3131, a “special document 2”mode 3132 and a “special document 3” mode 3133. The “special document 1”mode 3131 reproduces only texts from a printed matter that includes thetexts and texture pattern, for example, a certificate of an automobileinspection, by eliminating the texture pattern. The “special document 2”mode 3132 reproduces colored texts clearly included in a printed mattersuch as a form used for transferring money at a bank. The “specialdocument 3” mode 3133 raises density reproduction of a document such asan image printed by a dot printer, the document including an area whichdensity is supposed to be even but actually is uneven.

The above-described embodiments show cases wherein the present inventionis adapted to the composite device 100. However, the present inventionis not limited to the above-described embodiments, and can be adapted toa scanner. FIG. 32 is a block diagram showing a structure of a scanneraccording to a fifth embodiment of the present invention. Each unit witha number included in a scanner 270 shown in FIG. 32 corresponds to aunit with the same number included in a scanner part of the compositedevice 100 shown in FIG. 1. Additionally, the scanner 270 includes aninterface unit 271 that is used for transmitting image data to externalcomputers and applications. The scanner 270 controls input-densitycorrection and notch-density correction individually so as to executethe most appropriate density correction, where as a conventional scannercannot control the input-density correction and the use-densitycorrection individually. The input-density correction is correction ondensity characteristics that depend on an image reading process. Thenotch-density correction is linked with operation of a density notchprovided in the scanner 270. Accordingly, the scanner 270 can controlelimination of stains on the texture of a document and scanning of thedocument with a desirable density by use of the density notch, forexample.

The input-density-correction unit 103 is a processing unit that correctsdensity characteristics of a document depending on the document-readingunit 101, and converts a density signal-supplied from theshading-correction unit 102 to another digital signal whichcharacteristic is linear to density of an image recorded on a surface ofthe document. The density-correction unit 106 is a processing unit thatattends to density correction of a document read by the document-readingunit 101 according to image data and a variable threshold received fromthe spatial-filter-processing unit 105, and converts density to bereproduced according to an operation using the density notch. Theinput-density-correction unit 103 and the density-correction unit 106are individually controlled by an operation using the operation unit120. Accordingly, a desirable output image can be obtained by a simpleoperation using the operation unit 120 after registering, a combinationof setting of density correction executed by each of theinput-density-correction unit 103 and the density-correction unit 106.

A description will now be given of an image-processing system accordingto a sixth embodiment of the present invention with reference to FIG.33. An image-processing system 3300 shown in FIG. 33 includes animage-reading unit 3301, an image-recording unit 3302, afirst-density-correction unit 3303, a second-density-correction unit3304, a third-density-correction unit 3305, a control unit 3306, avideo-path-control unit 3307, and a system bus 3308. The control unit3306 is connected by the system bus 3308 to the units 3301, 3302, 3303,3304, 3305 and 3307. The video-path-control unit 3307 controls recordingof an image read by the image-reading unit 3301 by use of theimage-recording unit 3302, and exchanging of data between the anexternal application and the image-processing system 3300.

The first-density-correction unit 3303 executes correction on densitycharacteristics that depend on an image-reading process, that is,input-density correction. The second-density-correction unit 3304executes correction on characteristics to reproduce density of adocument according to an operation using a density notch provided in theimage-processing system 3300, that is, notch-density correction. Thethird density-correction unit 3305 executes correction on densitycharacteristics that depend on the image-recording unit 3302, that is,recording-density correction. The control unit 3306 controls each of thefirst-density-correction unit 3303, the second-density-correction unit3304 and the third-density-correction unit 3305 separately through thesystem bus 3308 so that each of the units 3303, 3304 and 3305 canexecute the most appropriate density correction on an input image. Theimage-processing system 3300 can control execution of the input-densitycorrection and the notch-density correction separately, whereas aconventional composite device controls the input-density correction andthe notch-density correction as a single density correction.Additionally, a user can adjust settings for the recording-densitycorrection in addition to the other density correction at once thoughthe control unit 3306 in the image-processing system 3300 according tothe sixth embodiment, whereas the user needs to adjust the setting forthe recording-density correction separately from the other densitycorrection in a conventional composite device.

As described above, the present invention is adapted to a compositedevice and a scanner. However, the present invention is not limited tothe above-described embodiments, and may be adapted to a printer. To beconcrete, a user can adjust the recording-density correction of aprinter by providing the recording-control unit 110 shown in FIG. 1 inthe printer.

The above description is provided in order to enable any person skilledin the art to make and use the invention and sets forth the best modecontemplated by the inventors of carrying out the invention.

The present invention is not limited to the specially disclosedembodiments and variations, and modifications may be made withoutdeparting from the scope and spirit of the invention.

The present application is based on Japanese Priority Application No.2000-264423, filed on Aug. 31, 2000, the entire contents of which arehereby incorporated by reference.

1. An image-processing device comprising: an image-reading unit thatreads image data from a document optically; an image-recording unit thatrecords the image data read onto recording paper; afirst-density-correction unit that corrects first densitycharacteristics that depend on said image-reading unit; asecond-density-correction unit that corrects second characteristics toreproduce density of the document; a third-density-correction unit thatcorrects third density characteristics that depend on saidimage-recording unit; and a control unit that independently controlseach of said first, second and third density-correction units to executedensity correction.
 2. The image-processing device as claimed in claim1, wherein said control unit includes a switch unit that switches afilter coefficient according to density of said image data, adata-correction unit that executes data correction according to adensity level, and a dot-correction unit that corrects formation of dotsto be recorded.
 3. The image-processing device as claimed in claim 2,wherein said switch unit includes a selection unit that sets acorrection coefficient individually for each of a low density area, ahigh density area, and an intermediate density area based on a fixedthreshold, and selects a selection signal.
 4. The image-processingdevice as claimed in claim 2, wherein said data-correction unit sets asignal different from said image data, and executes one of addition ofthe signal to the said image data and subtraction of the signal fromsaid image data, followed by executing a gradation-reproduction processon said image data.
 5. The image-processing device as claimed in claim2, wherein said dot-correction unit corrects data of adjacent pixels intwo dimensions based on arrangement of pixels.
 6. The image-processingdevice as claimed in claim 1, further comprising animage-quality-selecting unit that selects an image-quality mode, whereinsaid control unit controls one or three of the first, second, and thirddensity correction based on the image-quality mode selected by saidimage-quality-selecting unit.
 7. The image-processing device as claimedin claim 6, wherein said image-quality-selecting unit includes aparameter-grouping unit that collects parameters for density correctionas a group, and an image-quality-mode-assigning unit that assigns thegroup created by the parameter-grouping unit to an image-quality mode.8. The image-processing device as claimed in claim 7, wherein saidimage-quality-mode-assigning unit includes animage-quality-mode-selecting unit that selects an image-quality mode forregular use among a plurality of predetermined image-quality modes, animage-quality-correction unit that corrects characteristics of theimage-quality mode selected by the image-quality-mode-assigning unit, aparameter-adjusting unit that adjusts parameters for the characteristicsof the image-quality mode corrected by the image-quality-correctionunit, and a parameter-storing unit that stores the parameters for thecharacteristics of the image-quality mode adjusted by theparameter-adjusting unit.
 9. The image-processing device as claimed inclaim 7, wherein said image-quality-mode-assigning unit includes animage-quality-mode-selecting unit that selects an image-quality mode forregular use among a plurality of predetermined image-quality modes, animage-reading-correction unit that corrects image-readingcharacteristics of said image-processing device, animage-reading-parameter-adjusting unit that adjusts parameters for theimage-reading characteristics of the image-processing device correctedby the image-reading-correction unit, and animage-reading-parameter-storing unit that stores the parameters for theimage-reading characteristics of the image-processing device adjusted bythe image-reading-parameter-adjusting unit.
 10. The image-processingdevice as claimed in claim 7, wherein said image-quality-mode-assigningunit includes an image-quality-mode-selecting unit that selects animage-quality mode for regular use among a plurality of predeterminedimage-quality modes, a pixel-generation-correction unit that correctscharacteristics of pixel generation, a pixel-parameter-adjusting unitthat adjusts parameters for the characteristics of the pixel generationcorrected by the pixel-generation-correction unit, and apixel-parameter-storing unit that stores the parameters for thecharacteristics of the pixel generation adjusted by thepixel-parameter-adjusting unit.
 11. The image-processing device asclaimed in claim 7, wherein said image-quality-mode-assigning unitincludes an image-quality-mode-selecting unit that selects animage-quality mode for regular use among a plurality of predeterminedimage-quality modes, an image-quality-correction unit that correctscharacteristics of the image-quality mode selected by theimage-quality-mode-assigning unit, a relative-parameter-adjusting unitthat adjusts parameters for the characteristics of the image-qualitymode corrected by the image-quality-correction unit relatively to theparameters set once by the image-quality-correction unit, and aparameter-storing unit that stores the parameters for thecharacteristics of the image-quality mode adjusted by therelative-parameter-adjusting unit.
 12. The image-processing device asclaimed in claim 7, wherein said image-quality-mode-assigning unitincludes an image-quality-mode-selecting unit that selects animage-quality mode for regular use among a plurality of predeterminedimage-quality modes, an image-reading-correction unit that correctsimage-reading characteristics of said image-processing device, arelative-image-reading-parameter-adjusting unit that adjusts parametersfor the image-reading characteristics of the image-processing devicecorrected by the image-reading-correction unit relatively to theparameters once set by the image-reading-correction unit, and animage-reading-parameter-storing unit that stores the parameters for theimage-reading characteristics of the image-processing device adjusted bythe relative-image-reading-parameter-adjusting unit.
 13. Theimage-processing device as claimed in claim 7, wherein saidimage-quality-mode-assigning unit includes animage-quality-mode-selecting unit that selects an image-quality mode forregular use among a plurality of predetermined image-quality modes, apixel-generation-correction unit that corrects characteristics of pixelgeneration, a relative-pixel-parameter-adjusting unit that adjustsparameters for the characteristics of the pixel generation corrected bythe pixel-generation-correction unit relatively to the parameters onceset by the pixel-generation-correction unit, and apixel-parameter-storing unit that stores the parameters for thecharacteristics of the pixel generation adjusted by therelative-pixel-parameter-adjusting unit.
 14. A method of processing animage by use of an image-processing device that includes animage-reading unit, an image-recording unit, a first-density correctionunit, a second-density-correction unit and a third-density-correctionunit, said method comprising the steps of: reading image data from adocument optically by use of the image-reading unit; recording the imagedata on recording paper by use of the image-recording unit; correctingfirst density characteristics that depend on said image-reading unit byuse of the first-density-correction unit; correcting secondcharacteristics to reproduce density of the document by use of thesecond-density-correction unit; correcting third density characteristicsthat depend on said image-recording unit by use of the third-densitycorrection unit; and controlling said first-density-correction unit,said second-density-correction unit, and said third-density-correctionunit independently.
 15. The method as claimed in claim 14, furthercomprising the steps of: switching a filter coefficient according todensity of said image data; correcting data according to a densitylevel; and correcting formation of dots to be recorded.
 16. The methodas claimed in claim 15, further comprising the steps of: setting acorrection coefficient individually for each of a low density area, ahigh density area, and an intermediate density area based on a fixedthreshold; and selecting a selection signal among said low, high, andintermediate density areas.
 17. The method as claimed in claim 15,further comprising the steps of: setting a signal different from saidimage data; executing one of addition of the signal to the said imagedata and subtraction of the signal from said image data; and executing agradation-reproduction process on said image data.
 18. The method asclaimed in claim 15, further comprising the step of correcting data ofadjacent pixels in two dimensions based on arrangement of pixels. 19.The method as claimed in claim 14, further comprising the steps of:selecting an image-quality mode that determines a type of imageprocessing; and controlling density correction executed by one or all ofthe first, second, and third density correction units based on theimage-quality mode selected.
 20. The method as claimed in claim 19,further comprising the steps of: collecting parameters for the densitycorrection as a group; and assigning the created group to animage-quality mode.
 21. An image-processing device comprising: animage-reading unit that reads image data from a document optically; animage-recording unit that records the image data read by saidimage-reading unit onto recording paper; a first-density-correction unitthat corrects first density characteristics that depend on saidimage-reading unit; a second-density-correction unit that correctssecond characteristics to reproduce density of the document; and acontrol unit that independently controls each of said first and seconddensity-correction units to execute density correction based on animage-quality mode applied by an operation unit.
 22. Theimage-processing device as claimed in claim 21, wherein said operationunit includes an operation screen where image-quality modes aredisplayed, one of said image-quality modes being selected so that eachof said first and second density-correction units is adjustedindividually by the control unit.
 23. An image-processing devicecomprising: an image-reading unit that reads image data from a documentoptically; an image-recording unit that records the image data read bysaid image-reading unit onto recording paper; a density-correction unitthat corrects density characteristics that depend on saidimage-recording unit; and a control unit that independently controlssaid density-correction unit to execute density correction based on animage-quality mode applied by an operation unit, wherein a correctionpattern according to characteristics of the image-recording unit can beset independently from a correction pattern according to theimage-quality mode.
 24. The image-processing device as claimed in claim23, wherein said operation unit includes an operation screen whereimage-quality modes are displayed, one of said image-quality modes beingselected so that said density-correction unit is adjusted individuallyby the control unit.
 25. A method of processing an image by use of animage-processing device that includes an image-reading unit, animage-recording unit, a first-density correction unit and asecond-density-correction unit, said method comprising the steps of:reading image data from a document optically by use of the image-readingunit; recording the image data on recording paper by use of theimage-recording unit; correcting first density characteristics thatdepend on said image-reading unit by use of the first-density-correctionunit; correcting second characteristics to reproduce density of thedocument by use of the second-density-correction unit; and controllingsaid first-density-correction unit and said second-density-correctionunit independently.
 26. The method as claimed in claim 25, furthercomprising the steps of: selecting an image-quality mode that determinesa type of image processing; and controlling density correction executedby one or both of said first and second density-correction unitsindependently based on the image-quality mode selected.
 27. A method ofprocessing an image by use of an image-processing device that includesan image-reading unit, an image-recording unit and a density correctionunit, said method comprising the steps of: reading image data from adocument optically by use of the image-reading unit; recording the imagedata on recording paper by use of the image-recording unit; correctingdensity characteristics that depend on said image-recording unit by useof the density correction unit; and controlling said density-correctionunit independently; wherein a correction pattern according tocharacteristics of the image-recording unit can be set independentlyfrom a correction pattern according to the image-quality mode.
 28. Themethod as claimed in claim 27, further comprising the steps of:selecting an image-quality mode that determines a type of imageprocessing; and controlling density correction executed by saiddensity-correction unit independently based on the image-quality modeselected.
 29. A record medium readable by a machine, tangibly embodyinga program of instructions executable by the machine to perform methodsteps for processing an image by use of an image-processing device thatincludes an image-reading unit an image-recording unit, afirst-density-correction unit, a second-density-correction unit and athird-density-correction unit, said method steps comprising: readingimage data from a document optically by use of the image-reading unit;recording the image data on recording paper by use of theimage-recording unit; correcting first density characteristics thatdepend on said image-reading unit by use of the first-density-correctionunit; correcting second characteristics to reproduce density of thedocument by use of the second-density-correction unit; correcting thirddensity characteristics that depend on said image-recording unit by useof the third-density correction unit; and controlling saidfirst-density-correction unit, said second-density-correction unit, andsaid third-density-correction unit independently.
 30. The record mediumas claimed in claim 29, wherein said method steps comprising: selectingan image-quality mode that determines a type of image processing; andcontrolling density correction executed by said density-correction unitindependently based on the image-quality mode selected.
 31. Animage-processing system comprising: an image-reading unit that readsimage data from a document optically; an image-recording unit thatrecords the image data read onto recording paper; afirst-density-correction unit that corrects first densitycharacteristics that depend on said image-reading unit; asecond-density-correction unit that corrects second characteristics toreproduce density of the document; a third-density-correction unit thatcorrects third density characteristics that depend on saidimage-recording unit; a control unit that independently controls each ofsaid first, second and third density-correction units to execute densitycorrection; and an external-application interface that exchanges theimage data with an external application.
 32. The image-processing systemas claimed in claim 31, wherein the image data is transmitted throughsaid external-application interface to the external application afterbeing processed through said first and second density-correction unit.33. The image-processing system as claimed in claim 31, wherein theimage data is processed through said third-density-correction unit afterbeing received from the external application through saidexternal-application interface.
 34. The image processing device of claim23, wherein the correction pattern of the density correction unit isregisterable.
 35. The method of claim 27, wherein the correction patternof the density correction unit is registerable.